fix: hooks/python/flask-github-webhooks/Dockerfile to reduce vulnerab…

…ilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN12-ZLIB-6008963
- https://snyk.io/vuln/SNYK-DEBIAN12-GLIBC-1547196
- https://snyk.io/vuln/SNYK-DEBIAN12-GLIBC-1547196
- https://snyk.io/vuln/SNYK-DEBIAN12-TAR-1560620
- https://snyk.io/vuln/SNYK-DEBIAN12-SYSTEMD-6277507

hooks/python/flask-github-webhooks/Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.13.0b1-slim
+FROM python:3.13.0b3-slim
 LABEL version="1.0"
 LABEL description="Flask-based webhook receiver"