ci: switch to a manual cargo tarpaulin installation (#680)

Update to use a manual install of cargo tarpaulin, fixes the wrong filename being checked in the skip action.

.github/workflows/coverage.yml

@@ -20,24 +20,31 @@ jobs:
         with:
           concurrent_skipping: "same_content_newer"
           skip_after_successful_duplicate: "true"
-          paths: '["tests/**", "src/**", ".github/workflows/codecov.yml", ".cargo/**", "Cargo.toml", "Cargo.lock", "build.rs"]'
+          paths: '["tests/**", "src/**", ".github/workflows/coverage.yml", ".cargo/**", "Cargo.toml", "Cargo.lock", "build.rs"]'
           do_not_skip: '["workflow_dispatch"]'
 
   coverage:
     needs: pre_job
     if: ${{ needs.pre_job.outputs.should_skip != 'true' }}
     runs-on: ubuntu-latest
-    container:
-      image: xd009642/tarpaulin:develop
-      options: --security-opt seccomp=unconfined
-
     steps:
       - uses: actions/checkout@v2
 
+      - uses: actions-rs/toolchain@88dc2356392166efad76775c878094f4e83ff746 # https://github.com/actions-rs/toolchain/commit/88dc2356392166efad76775c878094f4e83ff746
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+          components: rustfmt
+
       - uses: Swatinem/rust-cache@842ef286fff290e445b90b4002cc9807c3669641 # 1.3.0
         with:
           key: ${{ matrix.triple.target }}
 
+      - name: Install tarpaulin
+        run: |
+          cargo install cargo-tarpaulin
+
       - name: Generate code coverage
         run: |
           cargo tarpaulin --verbose --all-features --workspace --run-types AllTargets --timeout 120 --out Xml