fix(ci): move workflows into .gitea directory

.gitea/workflows/build.yaml

@@ -0,0 +1,49 @@
+name: Build
+
+on:
+  pull_request:
+    types:
+    - opened
+    - reopened
+    - synchronize
+  push:
+    branches:
+    - master
+  workflow_dispatch: {}
+
+jobs:
+  build-arm64:
+    runs-on: ubuntu-latest-arm64
+    steps:
+      - uses: actions/checkout@v4.2.2
+      - uses: docker/setup-qemu-action@v3.6.0
+      - uses: docker/setup-buildx-action@v3.10.0
+
+      - name: Build image
+        run: |
+          TAG=latest
+
+          docker buildx build \
+            --platform linux/arm64 \
+            --file Dockerfile \
+            --provenance false \
+            --tag git.cryptic.systems/volker.raschek/helm:${TAG}-arm64 \
+            .
+
+  build-amd64:
+    runs-on: ubuntu-latest-amd64
+    steps:
+      - uses: actions/checkout@v4.2.2
+      - uses: docker/setup-qemu-action@v3.6.0
+      - uses: docker/setup-buildx-action@v3.10.0
+
+      - name: Build image
+        run: |
+          TAG=latest
+
+          docker buildx build \
+            --platform linux/amd64 \
+            --file Dockerfile \
+            --provenance false \
+            --tag git.cryptic.systems/volker.raschek/helm:${TAG}-amd64 \
+            .