Tag release with commit hash of the tip of current branch (#42)

At present, the tip of the default branch is tagged with the release.
This is not ideal if we want to make releases out of non-default
branches. Use the current commit ID as the input when invoking `cr
upload` so that the releases are tagged correctly.

Signed-off-by: Bharat Kunwar <bharat@stackhpc.com>

cr.sh

@@ -218,7 +218,7 @@ package_chart() {
 
 release_charts() {
     echo 'Releasing charts...'
-    cr upload -o "$owner" -r "$repo"
+    cr upload -o "$owner" -r "$repo" -c "$(git rev-parse HEAD)"
 }
 
 update_index() {