Fix broken tag script (#429)

Author: braydonk

internal/tools/scripts/tag.sh

@@ -20,7 +20,7 @@ set -e
 git tag -a ${GBOC_TAG} -m "Update to OpenTelemetry Collector version ${GBOC_TAG}"
 printf "Created git tag ${GBOC_TAG}. Would you like to push? (y/n) "
 read yn
-if [ $yn != ${yn#[Yy]} ]; then
+if [ "$yn" != "${yn#[Yy]}" ]; then
     git push origin ${GBOC_TAG}
 else
     git tag -d ${GBOC_TAG}