gh-40724: finding more deprecated stuff
    
namely all calls to "deprecated_function_alias" were missed by our
current script in tools

sequel of #39262

### 📝 Checklist

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
    
URL: #40724
Reported by: Frédéric Chapoton
Reviewer(s): Tobias Diez

Author: Release Manager

tools/check_deprecations.py

@@ -18,7 +18,7 @@
 from github.MainClass import Github
 
 # Regex pattern to find deprecation instances
-DEPRECATION_PATTERN = re.compile(r'deprecation\((\d+),')
+DEPRECATION_PATTERN = re.compile(r'(deprecation|deprecated_function_alias)\((\d+),')
 
 
 def get_pr_closed_date(github_token: str, pr_number: int) -> datetime: