Updated GHA config for 0.22.0-RC1

Author: mpilquist

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        scala: [2.12.10, 2.13.1, 0.22.0-bin-20200123-9982f0d-NIGHTLY]
+        scala: [2.12.10, 2.13.1, 0.22.0-RC1]
     steps:
     - uses: actions/checkout@v2
     - uses: olafurpg/setup-scala@v5