chore(semantic-release): disable pre-release

We have not used this recently at all and it is more
annoying than useful because it cannot work with rebases
which we do quite often.

package.json

@@ -65,11 +65,7 @@
   },
   "release": {
     "branches": [
-      "saga",
-      {
-        "name": "!(saga)",
-        "prerelease": true
-      }
+      "saga"
     ],
     "remoteTags": true,
     "plugins": [