Remove codecov since it does not work right now

Author: exoego

.travis.yml

@@ -13,16 +13,13 @@ jdk:
   - openjdk11
 
 install:
-  - rm -rf ~/.nvm && git clone https://github.com/nvm-sh/nvm.git ~/.nvm && (cd ~/.nvm && git checkout `git describe --abbrev=0 --tags`) && Ksource ~/.nvm/nvm.sh && nvm install $TRAVIS_NODE_VERSION
-  - pip install --user codecov
+  - rm -rf ~/.nvm &&
+    git clone https://github.com/nvm-sh/nvm.git ~/.nvm &&
+    (cd ~/.nvm && git checkout `git describe --abbrev=0 --tags`) &&
+    source ~/.nvm/nvm.sh && nvm install $TRAVIS_NODE_VERSION
 
 script:
-  - sbt ++$TRAVIS_SCALA_VERSION scalafmtSbtCheck scalafmtCheck test:scalafmtCheck clean current/doc core/doc coverage test
-  - if [[ "$TRAVIS_SCALA_VERSION" != 2.13.* ]]; # Primary support is 2.12.x
-    then
-      sbt ++$TRAVIS_SCALA_VERSION coverageReport coverageAggregate && codecov;
-    else echo "Skipping code coverage reporting on 2.13";
-    fi
+  - sbt ++$TRAVIS_SCALA_VERSION scalafmtSbtCheck scalafmtCheck test:scalafmtCheck clean current/doc core/doc test
 
 before_cache:
   - rm -fv $HOME/.ivy2/.sbt.ivy.lock