fix: releaser/Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN12-ZLIB-6008963
- https://snyk.io/vuln/SNYK-DEBIAN12-SHADOW-1559391
- https://snyk.io/vuln/SNYK-DEBIAN12-SHADOW-5423923
- https://snyk.io/vuln/SNYK-DEBIAN12-SHADOW-5423923
- https://snyk.io/vuln/SNYK-DEBIAN12-SHADOW-5879156

releaser/Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.12-slim-bookworm
+FROM python:3.14.0a3-slim-bookworm
 COPY releaser.py /releaser.py
 RUN pip install PyGithub --progress-bar off \
   && apt update -qq \