Add flag to codecov to differentiate scala versions

Author: DieBauer

.travis.yml

@@ -40,7 +40,7 @@ jobs:
       stage: test
       env: TEST="JVM tests"
       install: pip install --user codecov
-      script: sbt ++$TRAVIS_SCALA_VERSION! coverage buildJVM bench/test coverageReport && codecov
+      script: sbt ++$TRAVIS_SCALA_VERSION! coverage buildJVM bench/test coverageReport && codecov -F "$TRAVIS_SCALA_VERSION"
       scala: *scala_version_212
     - <<: *jvm_tests
       scala: *scala_version_213