Fix travis.yml (renamed to emacs-26.1-travis)

And removed emacs-25.1-travis. I'll be phasing out support for emacs <=
25.2.

.travis.yml

@@ -13,9 +13,8 @@ before_install:
   - cp init.test.el ~/.config/doom/init.el
   - INSECURE=1 YES=1 make install
 env:
-  - EVM_EMACS=emacs-25.1-travis
   - EVM_EMACS=emacs-25.3-travis
-  - EVM_EMACS=emacs-26-pretest-travis
+  - EVM_EMACS=emacs-26.1-travis
 script:
   - emacs --version
   - DEBUG=1 make test