Bump python from 3.12-alpine to 3.13-alpine in /semantic-conventions

Bumps python from 3.12-alpine to 3.13-alpine.

---
updated-dependencies:
- dependency-name: python
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

semantic-conventions/Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.12-alpine
+FROM python:3.13-alpine
 LABEL maintainer="The OpenTelemetry Authors"
 ADD *.whl /semconvgen/
 WORKDIR /semconvgen