[python-client] Modify python templates to resolve linting errors (#6839)

The linting results for the generated samples are as follows
where the first number is the BEFORE and the second is AFTER.

pyclient            7714 vs. 120
pyclient3           7717 vs. 120
pyclient3-asyncio   7584 vs. 120
pyclient-tornado    7633 vs. 120
pyclient3-tornado   7633 vs. 120

For the complete details please see the following gist.
https://gist.github.com/kenjones-cisco/2eb69a7e8db75e9fd53789f01570d9f2

Enforces linting for python clients by running flake8 for the generated
python client.

samples/client/petstore/python-asyncio/docs/PetApi.md

@@ -21,7 +21,7 @@ Add a new pet to the store
 
 
 
-### Example 
+### Example
 ```python
 from __future__ import print_function
 import time
@@ -37,7 +37,7 @@ configuration.access_token = 'YOUR_ACCESS_TOKEN'
 api_instance = petstore_api.PetApi(petstore_api.ApiClient(configuration))
 body = petstore_api.Pet() # Pet | Pet object that needs to be added to the store
 
-try: 
+try:
     # Add a new pet to the store
     api_instance.add_pet(body)
 except ApiException as e:
@@ -72,7 +72,7 @@ Deletes a pet
 
 
 
-### Example 
+### Example
 ```python
 from __future__ import print_function
 import time
@@ -89,7 +89,7 @@ api_instance = petstore_api.PetApi(petstore_api.ApiClient(configuration))
 pet_id = 789 # int | Pet id to delete
 api_key = 'api_key_example' # str |  (optional)
 
-try: 
+try:
     # Deletes a pet
     api_instance.delete_pet(pet_id, api_key=api_key)
 except ApiException as e:
@@ -125,7 +125,7 @@ Finds Pets by status
 
 Multiple status values can be provided with comma separated strings
 
-### Example 
+### Example
 ```python
 from __future__ import print_function
 import time
@@ -141,7 +141,7 @@ configuration.access_token = 'YOUR_ACCESS_TOKEN'
 api_instance = petstore_api.PetApi(petstore_api.ApiClient(configuration))
 status = ['status_example'] # list[str] | Status values that need to be considered for filter
 
-try: 
+try:
     # Finds Pets by status
     api_response = api_instance.find_pets_by_status(status)
     pprint(api_response)
@@ -177,7 +177,7 @@ Finds Pets by tags
 
 Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
 
-### Example 
+### Example
 ```python
 from __future__ import print_function
 import time
@@ -193,7 +193,7 @@ configuration.access_token = 'YOUR_ACCESS_TOKEN'
 api_instance = petstore_api.PetApi(petstore_api.ApiClient(configuration))
 tags = ['tags_example'] # list[str] | Tags to filter by
 
-try: 
+try:
     # Finds Pets by tags
     api_response = api_instance.find_pets_by_tags(tags)
     pprint(api_response)
@@ -229,7 +229,7 @@ Find pet by ID
 
 Returns a single pet
 
-### Example 
+### Example
 ```python
 from __future__ import print_function
 import time
@@ -247,7 +247,7 @@ configuration.api_key['api_key'] = 'YOUR_API_KEY'
 api_instance = petstore_api.PetApi(petstore_api.ApiClient(configuration))
 pet_id = 789 # int | ID of pet to return
 
-try: 
+try:
     # Find pet by ID
     api_response = api_instance.get_pet_by_id(pet_id)
     pprint(api_response)
@@ -283,7 +283,7 @@ Update an existing pet
 
 
 
-### Example 
+### Example
 ```python
 from __future__ import print_function
 import time
@@ -299,7 +299,7 @@ configuration.access_token = 'YOUR_ACCESS_TOKEN'
 api_instance = petstore_api.PetApi(petstore_api.ApiClient(configuration))
 body = petstore_api.Pet() # Pet | Pet object that needs to be added to the store
 
-try: 
+try:
     # Update an existing pet
     api_instance.update_pet(body)
 except ApiException as e:
@@ -334,7 +334,7 @@ Updates a pet in the store with form data
 
 
 
-### Example 
+### Example
 ```python
 from __future__ import print_function
 import time
@@ -352,7 +352,7 @@ pet_id = 789 # int | ID of pet that needs to be updated
 name = 'name_example' # str | Updated name of the pet (optional)
 status = 'status_example' # str | Updated status of the pet (optional)
 
-try: 
+try:
     # Updates a pet in the store with form data
     api_instance.update_pet_with_form(pet_id, name=name, status=status)
 except ApiException as e:
@@ -389,7 +389,7 @@ uploads an image
 
 
 
-### Example 
+### Example
 ```python
 from __future__ import print_function
 import time
@@ -407,7 +407,7 @@ pet_id = 789 # int | ID of pet to update
 additional_metadata = 'additional_metadata_example' # str | Additional data to pass to server (optional)
 file = '/path/to/file.txt' # file | file to upload (optional)
 
-try: 
+try:
     # uploads an image
     api_response = api_instance.upload_file(pet_id, additional_metadata=additional_metadata, file=file)
     pprint(api_response)