Finish building Postgres support (#133)

This includes:
 - Building a Docker image for Postgres as well as SQLite
 - Fuller instructions for usage of the package, including the Postgres builds.

A few related things changed here:
 - `.env` is not used anymore -- the defaults in the Dockerfiles are
   sufficient
 - The Rust version in the Dockerfiles is increased to match the MSRV,
   and with it the Alpine version bumped to one built with that Rust
   version.
 - Cargo dependencies on native-tls and openssl updated to include only
   the `vendored` feature, so as not to require a system openssl
   installation.
 - Two GitHub jobs are set up, to build the two different Docker images
 - The documentation incorrectly suggested using `DELETE .. CASCADE` to
   delete clients. This syntax does not exist, as the cascading delete
   is configured in the schema.

.github/workflows/docker.yml

@@ -6,17 +6,13 @@ on:
       - '*'
 
 jobs:
-  docker:
+  sqlite:
     runs-on: ubuntu-latest
     steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-      - name: Load .env file
-        uses: xom9ikk/dotenv@v2
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v3
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
       - name: Login to ghcr.io
         uses: docker/login-action@v3
         with:
@@ -24,11 +20,11 @@ jobs:
           username: ${{ github.repository_owner }}
           password: ${{ secrets.GITHUB_TOKEN }}
       - name: Docker meta
-        id: meta
+        id: meta-sqlite
         uses: docker/metadata-action@v5
         with:
           images: |
-            ghcr.io/${{ github.repository }}
+            ghcr.io/gothenburgbitfactory/taskchampion-sync-server
           tags: |
             type=ref,event=branch
             type=semver,pattern={{version}}
@@ -38,10 +34,39 @@ jobs:
         uses: docker/build-push-action@v6
         with:
           context: .
+          path: "{context}/Dockerfile-sqlite"
           platforms: linux/amd64,linux/arm64
           push: true
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
-          build-args: |
-            ALPINE_VERSION=${{ env.ALPINE_VERSION }}
-            RUST_VERSION=${{ env.RUST_VERSION }}
+          tags: ${{ steps.meta-sqlite.outputs.tags }}
+          labels: ${{ steps.meta-sqlite.outputs.labels }}
+  postgres:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Login to ghcr.io
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Docker meta
+        id: meta-postgres
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            ghcr.io/gothenburgbitfactory/taskchampion-sync-server-postgres
+          tags: |
+            type=ref,event=branch
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=match,pattern=\d.\d.\d,value=latest
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          path: "{context}/Dockerfile-postgres"
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta-postgres.outputs.tags }}
+          labels: ${{ steps.meta-postgres.outputs.labels }}