ci: try using setup-pixi action

.github/workflows/ci.yml

@@ -23,20 +23,16 @@ jobs:
         with:
           components: rustfmt, clippy
       - uses: Swatinem/rust-cache@v2
-      - name: Install Pixi
+      - uses: prefix-dev/[email protected]
+        with:
+          activate-environment: true
+          cache: true
+          cache-write: ${{ github.event_name == 'push' && github.ref_name == 'main' }}
+          manifest-path: build/pixi.toml
+      - name: Tweak environment to find GDAL
         run: |
-          curl -fsSL https://pixi.sh/install.sh | bash
-          echo "$HOME/.pixi/bin" >> $GITHUB_PATH
-          echo "GDAL_HOME=$(pwd)/build/.pixi/envs/default" >> "$GITHUB_ENV"
-          echo "LD_LIBRARY_PATH=$(pwd)/build/.pixi/envs/default/lib" >> "$GITHUB_ENV"
-          echo "GEOS_LIB_DIR=$(pwd)/build/.pixi/envs/default/lib" >> "$GITHUB_ENV"
-          # TODO: infer from toml file/lockfile
-          echo "GEOS_VERSION=3.12.1" >> "$GITHUB_ENV"
           echo "PKG_CONFIG_PATH=$(pwd)/build/.pixi/envs/default/lib/pkgconfig" >> "$GITHUB_ENV"
-      - name: Install build requirements
-        run: |
-          cd build
-          pixi install
+          echo "LD_LIBRARY_PATH=$(pwd)/build/.pixi/envs/default/lib" >> "$GITHUB_ENV"
       - name: Fmt
         run: cargo fmt -- --check
       - name: Clippy