Remove unneeded anchors from OSX shards

Turns out Precise comes installed with 3.6 when requested! So we only need Pyenv for OSX, not Linux.

.travis.yml

@@ -16,7 +16,7 @@ osx_setup: &osx_setup
       packages:
         - openssl
   env:
-    - &env_pyenv >
+    - >
       PYENV_ROOT="${HOME}/.pyenv"
       PATH="${PYENV_ROOT}/shims:${PATH}"
     - >
@@ -26,7 +26,7 @@ osx_setup: &osx_setup
       LDFLAGS="-L/usr/local/opt/openssl/lib"
       CPPFLAGS="-I/usr/local/opt/openssl/include"
   before_install:
-    - &pyenv_install_py36 >
+    - >
       git clone https://github.com/pyenv/pyenv ${PYENV_ROOT}
       && ${PYENV_ROOT}/bin/pyenv install 3.6.8
       && ${PYENV_ROOT}/bin/pyenv global 3.6.8