Use the codecov as own step, not with default build

.github/workflows/ci.yml

@@ -253,3 +253,34 @@ jobs:
         uses: scalacenter/sbt-dependency-submission@v2
         with:
           configs-ignore: test scala-tool scala-doc-tool test-internal
+
+  coverage:
+    name: Generate coverage report
+    strategy:
+      matrix:
+        os: [ubuntu-latest]
+        scala: [2.13, 2.12, 3]
+        java: [temurin@11]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - name: Checkout current branch (fast)
+        uses: actions/checkout@v4
+
+      - name: Setup Java (temurin@17)
+        id: setup-java-temurin-17
+        if: matrix.java == 'temurin@17'
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 17
+          cache: sbt
+
+      - name: sbt update
+        if: matrix.java == 'temurin@17' && steps.setup-java-temurin-17.outputs.cache-hit == 'false'
+        run: sbt +update
+
+      - run: sbt '++ ${{ matrix.scala }}' coverage root/test coverageAggregate
+
+      - uses: codecov/codecov-action@v3
+        with:
+          flags: ${{matrix.scala}}

build.sbt

@@ -11,6 +11,7 @@ ThisBuild / tlCiScalafixCheck := false // TODO: Address these in a follow up PR
 ThisBuild / tlFatalWarnings := false // TODO: fix by dropping 2.12
 ThisBuild / tlCiReleaseTags := true
 ThisBuild / tlCiReleaseBranches := Nil
+ThisBuild / circeRootOfCodeCoverage := Some("root")
 
 val circeVersion = "0.14.9"
 val munitVersion = "1.0.0"
@@ -26,8 +27,6 @@ def priorTo2_13(scalaVersion: String): Boolean =
 val baseSettings = Seq(
   resolvers ++= Resolver.sonatypeOssRepos("releases"),
   resolvers ++= Resolver.sonatypeOssRepos("snapshots"),
-  coverageHighlighting := true,
-  coverageEnabled := !tlIsScala3.value,
   libraryDependencies ++= Seq(
     "io.circe" %% "circe-core" % circeVersion,
     "org.scala-lang.modules" %% "scala-collection-compat" % "2.12.0",