ci: bump cache-nix-action

Author: ethanndickson

.github/actions/nix-devshell/action.yaml

@@ -6,7 +6,7 @@ runs:
     - name: Setup Nix
       uses: nixbuild/nix-quick-install-action@5bb6a3b3abe66fd09bbf250dce8ada94f856a703 # v30
 
-    - uses: nix-community/cache-nix-action@92aaf15ec4f2857ffed00023aecb6504bb4a5d3d # v6
+    - uses: nix-community/cache-nix-action@135667ec418502fa5a3598af6fb9eb733888ce6a # v6.1.3
       with:
         # restore and save a cache using this key
         primary-key: nix-${{ runner.os }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}