build(ci): fix coverage workflow

.github/workflows/ci.yml

@@ -1,4 +1,10 @@
 name: CI
+# If new code is pushed to a PR branch, then cancel in progress workflows for
+# that PR. Ensures that we don't waste CI time, and returns results quicker.
+# https://github.com/jonhoo/rust-ci-conf/pull/5
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
 
 on:
   push:
@@ -53,7 +59,7 @@ jobs:
     runs-on: ubuntu-latest
     name: ubuntu / stable / coverage
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install stable
@@ -67,7 +73,11 @@ jobs:
         run: cargo generate-lockfile
       - name: cargo llvm-cov
         run: cargo llvm-cov --locked --all-features --lcov --output-path lcov.info
+      - name: Record Rust version
+        run: echo "RUST=$(rustc --version)" >> "$GITHUB_ENV"
       - name: Upload to codecov.io
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           fail_ci_if_error: true
+          token: ${{ secrets.CODECOV_TOKEN }}
+          env_vars: OS,RUST

README.md

@@ -146,7 +146,7 @@ contract HashPairTest {
 
 This Solidity file is missing the tests for the branch
 `When first arg is bigger than second arg`, which would be reported after
-running `bulloak check`, like so:
+running `bulloak check tests/scaffold/basic.tree`, like so:
 
 ```text
 warn: function "test_WhenFirstArgIsBiggerThanSecondArg" is missing in .sol