Update scala-library to 2.12.19

Author: scalameta-bot

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        scala: [2.12.18, 2.13.12]
+        scala: [2.12.19, 2.13.12]
         os: [ubuntu-latest]
         java: [11, 8]
     steps: