chore: Further tweaks to version string (#1895)

* fix: Only define SUFFIX if PR or BRANCH build
Also, only define `VERSION_TAG` if VERSION_TAG exists.

* fix: Omit GIT SHA for colorlcd also if a tagged build

tools/build-gh.sh

@@ -58,7 +58,7 @@ elif [[ $gh_type = "pull" ]]; then
   # pull: refs/pull/<pr_number>/merge
   gh_pull_number=PR$(echo "$GITHUB_REF" | awk -F / '{print $3}')
   export EDGETX_VERSION_SUFFIX=$gh_pull_number
-else
+elif [[ $gh_type = "heads" ]]; then
   # heads: refs/heads/<branch_name>
   gh_branch=${GITHUB_REF##*/}
   export EDGETX_VERSION_SUFFIX=$gh_branch