chore: remove hardcoded Go version and use go.mod for versioning in workflows

Author: dido18

.github/workflows/go-test.yml

@@ -6,8 +6,6 @@ on:
   pull_request:
     branches: [main]
 
-env:
-  GO_VERSION: "1.25.1"
 
 jobs:
   go-test:
@@ -19,7 +17,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v5
         with:
-          go-version: ${{ env.GO_VERSION }}
+          go-version-file: go.mod
 
       - name: Run tests
         run: go tool task test

.github/workflows/release.yml

@@ -6,7 +6,6 @@ on:
       - "[0-9]+.[0-9]+.[0-9]+*"
 
 env:
-  GO_VERSION: "1.25.1"
   PROJECT_NAME: "arduino-router"
   GITHUB_TOKEN: ${{ secrets.ARDUINOBOT_TOKEN }}
   GITHUB_USERNAME: ArduinoBot
@@ -34,7 +33,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v5
         with:
-          go-version: ${{ env.GO_VERSION }}
+          go-version-file: go.mod
 
       - name: Build deb
         run: |