[#179] cargo-tarpaulin install caching

Author: myyrakle

.github/workflows/coverage.yml

@@ -37,7 +37,7 @@ jobs:
             ~/.cargo/git/db/
 
       - name: Install cargo-tarpaulin
-        run: cargo install cargo-tarpaulin
+        run: cargo install cargo-tarpaulin --locked
 
       - name: Run cargo-tarpaulin
         run: |