build: remove redundant pyenv call in Travis build

PR-URL: #27247
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>

.travis.yml

@@ -40,7 +40,6 @@ jobs:
         - cp out/Release/node /home/travis/.ccache
         - cp out/Release/cctest /home/travis/.ccache
 
-        - pyenv global 2.7.15
     - stage: "Tests"
       name: "Test JS Suites"
       cache: ccache