Revert "Build snap based on branch instead of tag"

This reverts commit 2e5dd05a6c.

snap/snapcraft.yaml

@@ -37,6 +37,11 @@ parts:
       else
         GRADE=stable
       fi
+      if [ "$VERSION" = "$TAG" ] && [ ! "$VERSION" = "${VERSION%-beta}" ]; then
+        BRANCH=beta
+      elif [ "$VERSION" = "$TAG" ]; then
+        BRANCH=master
+      fi
       echo $BRANCH > branch.txt
       echo $COMMIT > version.txt
       snapcraftctl set-version "$VERSION"