Add go.mod and GH actions

.github/workflows/test.yml

@@ -0,0 +1,33 @@
+on:
+  push:
+    tags:
+      - v*
+    branches:
+      - master
+  pull_request:
+name: Test
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.21.x, 1.22.x]
+        platform: [ubuntu-latest]
+    runs-on: ${{ matrix.platform }}
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v4
+      with:
+        go-version: ${{ matrix.go-version }}
+    - name: Checkout code
+      uses: actions/checkout@v3
+    - uses: actions/cache@v3
+      with:
+        path: ~/go/pkg/mod
+        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-go-
+    - name: Get dependencies
+      run: go get ./...
+    - name: Test
+      run: |
+        go test ./...

go.mod

@@ -0,0 +1,3 @@
+module github.com/koofr/resize
+
+go 1.21