fix(ci): Regex correctly matches tags when doing release

Before this patch, a branch name like `1.0.0-testing-something` was
considered as being the source of a release.

With this new regex we ensure we never use a wrong tag/branch to create
a release.

.github/workflows/main.yaml

@@ -26,7 +26,7 @@ jobs:
         run: |
           VERSION=${GITHUB_REF/refs\/tags\//}
           echo ::set-output name=VERSION::${VERSION}
-          DOING_RELEASE=$(echo $VERSION | grep -c '[0-9]\+\.[0-9]\+\.[0-9]\+\(-.*\)\?' || true)
+          DOING_RELEASE=$(echo $VERSION | grep -c '^[0-9]\+\.[0-9]\+\.[0-9]\+\(-\([a-zA-Z]\+\)?[0-9]*\)\?$' || true)
           echo ::set-output name=DOING_RELEASE::${DOING_RELEASE}
           echo $VERSION
           echo $DOING_RELEASE