Removes dead travis.yml.

Travis never worked; GitHub actions do; that's CI.

.travis.yml

@@ -1,13 +0,0 @@
-# language: objective-c
-# osx_image: xcode8.2
-# xcode_project: OSBindings/Mac/Clock Signal.xcodeproj
-# xcode_scheme: Clock Signal
-# xcode_sdk: macosx10.12
-
-language: cpp
-before_install:
-	- sudo apt-get install libsdl2-dev
-script: cd OSBindings/SDL && scons
-compiler:
-	- clang
-	- gcc