Remove the Scala 2.11.x branch, since we do not support it anymore.

Author: sjrd

Diff for: .github/workflows/nightly.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        scalabranch: ["2.11.x", "2.12.x", "2.13.x"]
+        scalabranch: ["2.12.x", "2.13.x"]
         scalajsbranch: ["main"]
     env:
       SCALA_BRANCH: "${{ matrix.scalabranch }}"