ci: pin cargo-tarpaulin version (#652)

Also, current 0.27.3 version pulls dependencies that require Rust 1.74.

.github/workflows/ci.yml

@@ -204,13 +204,14 @@ jobs:
       - uses: actions-rs/toolchain@63eb9591781c46a70274cb3ebdf190fce92702e8 # v1
         with:
           profile: minimal
-          toolchain: 1.70.0
+          toolchain: 1.74.0
           override: true
           components: rustfmt
       - uses: actions-rs/install@69ec87709ffb5b19a7b5ddbf610cb221498bb1eb # v0.1.2
         with:
           crate: cargo-tarpaulin
           use-tool-cache: true
+          version: 0.27.3
       - run: cargo tarpaulin --verbose --ignore-tests --all-features --timeout=600 --out xml
       - name: Upload to codecov.io
         run: |