Update scala-library to 2.12.20

Author: slick-scala-steward[bot]

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        scala: [2.12.19]
+        scala: [2.12.20]
         java: [zulu@11]
     runs-on: ${{ matrix.os }}
     steps: