fix(api-gateway): non-greedy route pattern regex

[heitorlessa]

Issue #, if available: #520

Description of changes:

This fixes a regex bug that used a greedy pattern ending with incorrect path resolution, as any path after a pattern would be included in the argument.

Excerpt:

@app.get("/accounts/<account_id>")
def get_account(account_id: str):
    print(f"Account ID ({account_id}) would be 123")

# Greedy regex would inject the incorrect function parameter
@app.get("/accounts/<account_id>/source_networks")
def get_account_networks(account_id: str):
    print(f"Account ID ({account_id}) would be 123/source_networks")

In this example, say we have a GET request as /accounts/123 and another as /accounts/123/source_networks, we'd have the following effect prior to this fix:

Function	Regex	Effective account_id value
get_account	r'^/accounts/(?P<account_id>.+)$'	123
get_account_networks	r'^/accounts/(?P<account_id>.+)/source_networks$'	123/source_networks

With this fix, account_id parameter would be 123 in both occasions due to word boundary not being non-greedy. This also allows an arbitrary number of dynamic route paths and static route paths.

Function	Regex	Effective account_id value
get_account	r'^/accounts/(?P<account_id>\\w+\\b)$'	123
get_account_networks	r'^/accounts/(?P<account_id>\\w+\\b)/source_networks$'	123

Checklist

• Meet tenets criteria
• Update tests
• PR title follows conventional commit semantics

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[codecov-commenter]

Codecov Report

Merging #533 (59d91e9) into develop (018a91b) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop     #533   +/-   ##
========================================
  Coverage    99.19%   99.19%           
========================================
  Files          113      113           
  Lines         4476     4478    +2     
  Branches       243      243           
========================================
+ Hits          4440     4442    +2     
  Misses          24       24           
  Partials        12       12           

Impacted Files	Coverage Δ
aws_lambda_powertools/event_handler/api_gateway.py	100.00% <100.00%> (ø)

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[heitorlessa]

Note: one other bug and potential minor issue to address as part of 1.18 release or the next one after that

1. Raise an exception if the same function has been registered for a separate route rule

2. App.route decorator doesn't preserve fn signature and will likely fail Mypy like tracer.capture_method older bug