migrate from drone to gitea actions

.gitea/workflows/ynab-portfolio-monitor.yaml

@@ -0,0 +1,40 @@
+name: ynab-portfolio-monitor
+
+on:
+  push:
+    branches:
+      - main
+      - master
+  pull_request: {}
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "1.x"
+          cache: true        # enables Go module + build caching automatically
+
+      - name: Build server
+        env:
+          GOOS: linux
+          GOARCH: amd64
+          CGO_ENABLED: 0
+        run: |
+          go version
+          go build -a -ldflags "-w"
+          cp "$(go env GOROOT)/lib/time/zoneinfo.zip" .
+          cp /etc/ssl/certs/ca-certificates.crt .
+
+      - name: Build Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          push: true
+          tags: registry.stevenpolley.net/ynab-portfolio-monitor:latest