Revert "ci: cache cargo registry and target between Flatpak builds"

This reverts commit 11def894e2.

.gitea/workflows/build-flatpak.yml

@@ -106,7 +106,7 @@ jobs:
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal
           echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
 
-      - name: Fetch upstream source
+      - name: Build agent from upstream source
         if: steps.check.outputs.build == 'true'
         env:
           TOKEN: ${{ secrets.HeiniRemoteFlatpakActionReleases }}
@@ -117,23 +117,7 @@ jobs:
           git -C upstream remote add origin "$UPSTREAM_URL"
           git -C upstream fetch -q --depth 1 origin "${{ steps.ver.outputs.ref }}"
           git -C upstream checkout -q FETCH_HEAD
-
-      # Same cache layout as the upstream workflows: without it every build
-      # compiled all dependencies from scratch (the bulk of the job's time).
-      - name: Cache cargo
-        if: steps.check.outputs.build == 'true'
-        uses: actions/cache@v4
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-            upstream/target
-          key: cargo-flatpak-${{ hashFiles('upstream/Cargo.lock') }}
-          restore-keys: cargo-flatpak-
-
-      - name: Build agent from upstream source
-        if: steps.check.outputs.build == 'true'
-        run: cargo build --release -p heiniremote-agent --manifest-path upstream/Cargo.toml
+          cargo build --release -p heiniremote-agent --manifest-path upstream/Cargo.toml
 
       - name: Install Flatpak runtime and SDK
         if: steps.check.outputs.build == 'true'