Update .travis.yml
diff --git a/.travis.yml b/.travis.yml
index 59358fd..175deb4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,22 +2,21 @@
 
 os: linux
 otp_release:
+  - 21.0
   - 20.0
   - 19.3
   - 18.3
 
-script: rebar3 eunit
 install:
-  - wget https://s3.amazonaws.com/rebar3/rebar3 && chmod +x rebar3
   - sudo pip install codecov
 script:
-  - ./rebar3 compile
-  - ./rebar3 xref
-  - ./rebar3 eunit
-  - ./rebar3 dialyzer
-  - ./rebar3 edoc
-  - ./rebar3 cover
-  - ./rebar3 covertool generate
+  - rebar3 compile
+  - rebar3 xref
+  - rebar3 eunit
+  - rebar3 dialyzer
+  - rebar3 edoc
+  - rebar3 cover
+  - rebar3 as test covertool generate
   - cp _build/test/covertool/jaeger_passage.covertool.xml ./cobertura.xml
 
 after_success: