ci: use local Go toolchain and downgrade Go version

.github/workflows/golangci-lint.yml

@@ -20,14 +20,19 @@ jobs:
   golangci:
     name: lint
     runs-on: ubuntu-latest
+    env:
+      GOTOOLCHAIN: local
     strategy:
       matrix:
-        go: ['1.24']
+        go: ['1.23', '1.24']
     steps:
+      - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
         with:
           go-version: ${{ matrix.go }}
-      - uses: actions/checkout@v4
+
+      - name: Tidy
+        run: go mod tidy
 
       - name: Format
         run: go fmt

.github/workflows/test.yml

@@ -7,6 +7,8 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
+    env:
+      GOTOOLCHAIN: local
     strategy:
       fail-fast: false
       matrix:

go.mod

@@ -1,6 +1,6 @@
 module github.com/pires/go-proxyproto
 
-go 1.24
+go 1.23
 
 require golang.org/x/net v0.39.0