chore: Fix coverage (#16)

Author: lukesneeringer

.github/workflows/coverage.yaml

@@ -18,7 +18,7 @@ jobs:
         run: cargo install cargo-tarpaulin
       - name: Generate code coverage
         run: |
-          cargo tarpaulin --verbose --out xml --engine llvm --features serde,easter
+          cargo tarpaulin --verbose --out xml --engine llvm
         env:
           CARGO_NET_GIT_FETCH_WITH_CLI: true
       - name: Upload to codecov.io