Normalise names of Python identifiers

[viennadd]

Found 2 situations in special characters naming and parameter naming would cause conflicts with Python identifiers.

Case 1:

I have found that there is a dollar sign '$' character in operationId which will be converted to the name of the method, resulting invalid method name in Python

"/v1/diffs": {
	"post": {
		"tags": [
		],
		"summary": "Get Groups",
		"operationId": "get_grou##ps_$v1_ex%%ports_gr.oups__post",
		"parameters": [
		],

Case 2:

The next issue can be triggered by naming a query parameter name to one of the Python keywords.

"/v1/diffs": {
	"post": {
		"tags": [
		],
		"summary": "Get Groups",
		"operationId": "get_groups_v1_exports_groups__post",
		"parameters": [
			{
				"required": true,
				"schema": {
					"title": "from_sha of a diff",
					"type": "string"
				},
				"name": "from",
				"in": "query"
			}
		],

[MarcoMuellner]

@viennadd Can you add some tests for these cases?

The current test suite is also failing. Please take a look at that :)

[viennadd]

@viennadd Can you add some tests for these cases?

The current test suite is also failing. Please take a look at that :)

I have added two test cases to demonstrate the issues,
Though I am not sure why the test suite are failing (

[viennadd]

@viennadd Can you add some tests for these cases?

The current test suite is also failing. Please take a look at that :)

Test suite is ready now, it was my first time using codecov.io ( yep
The failure of test action was causing by the missing of CODECOV_TOKEN in my repo fork *_*

[MarcoMuellner]

Love it, thank you for the contribution!