update dependencies, add premerge

.github/workflows/premerge.yaml

@@ -0,0 +1,25 @@
+name: Unit tests, lint, and build
+
+on:
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Go
+        uses: actions/setup-go@v4
+        with:
+          go-version: '1.21'
+
+      - name: Build
+        run: go build -v ./...
+
+      - name: Test
+        run: go test -v ./...
+
+      - name: Lint
+        run: pre-commit run --all-files

go.mod

@@ -1,6 +1,6 @@
 module github.com/thought-machine/spot-interruption-exporter
 
-go 1.20
+go 1.21
 
 require (
 	cloud.google.com/go/compute v1.23.3