Filter out extra line when searching for release origin branch

lately, but not always, the output of `git branch -a --contains` started
to include one extra line:

```
  remotes/origin/HEAD -> origin/dev
  remotes/origin/dev
```

The `remotes/origin/HEAD -> origin/dev` is what breaks the sanity check
script b/c this is something new, that git has started to report in its
output. For example broke here:
https://github.com/gluwa/creditcoin3/actions/runs/12985577903/job/36210711957

but not here:
https://github.com/gluwa/creditcoin3/actions/runs/12914730298/job/36014957248

.github/check-tag-suffix-vs-origin-branch.sh

@@ -11,7 +11,7 @@ echo "----- DEBUG -----"
 git branch -a --contains | grep remotes/origin
 echo "----- END -----"
 
-NEAREST_GIT_BRANCH=$(git branch -a --contains | grep remotes/origin | cut -f3 -d/)
+NEAREST_GIT_BRANCH=$(git branch -a --contains | grep -v remotes/origin/HEAD | grep remotes/origin | cut -f3 -d/)
 
 echo "INFO: git tag: '$GIT_TAG'"
 echo "INFO: suffix from git tag: '$SUFFIX_FROM_GIT_TAG'"