chore(python-runtime): remove pinned version of libexpat (#3844)

Signed-off-by: odubajDT <ondrej.dubaj@dynatrace.com>
Signed-off-by: odubajDT <93584209+odubajDT@users.noreply.github.com>
Co-authored-by: Moritz Wiesinger <moritz.wiesinger@dynatrace.com>

runtimes/python-runtime/Dockerfile

@@ -6,7 +6,7 @@ LABEL org.opencontainers.image.source="https://github.com/keptn/lifecycle-toolki
     org.opencontainers.image.vendor="Keptn" \
     org.opencontainers.image.licenses="Apache-2.0"
 
-RUN apk --no-cache add curl libexpat==2.6.3-r0
+RUN apk --no-cache add curl
 
 RUN pip install -q --disable-pip-version-check pyyaml GitPython requests