fix: correct go.mod to 1.24 (go 1.25 does not exist)

Also use go-version-file in CI so go.mod and workflow stay in sync.

.forgejo/workflows/test.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Set up Go
         uses: https://github.com/actions/setup-go@v5
         with:
-          go-version: '1.24'
+          go-version-file: go.mod
 
       - name: Test
         run: go test -race -v ./...

go.mod

@@ -1,6 +1,6 @@
 module github.com/metamorphosis-dev/kafka
 
-go 1.25.0
+go 1.24
 
 require (
 	github.com/BurntSushi/toml v1.5.0