Update permissions to hopefully push successfully now (rust-lang#469)

* Update permissions to hopefully push successfully now

* put permissions in the right spot

Author: tedinski

.github/workflows/rmc.yml

@@ -9,6 +9,8 @@ jobs:
     strategy:
       matrix:
         os: [macos-10.15, ubuntu-18.04, ubuntu-20.04]
+    permissions:
+      contents: write
     steps:
       - name: Checkout RMC
         uses: actions/checkout@v2