Update erlef/setup-beam action to v1.21.0

Author: renovate[bot]

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
-      - uses: erlef/setup-beam@e6d7c94229049569db56a7ad5a540c051a010af9 # v1.20.4
+      - uses: erlef/setup-beam@3580539ceec3dc05b0ed51e9e10b08eb7a7c2bb4 # v1.21.0
         id: beam
         with:
           version-file: .tool-versions