Update .travis.yml

Author: Zialus

.travis.yml

@@ -239,7 +239,7 @@ matrix:
 
     # CLANG
     - os: osx
-      osx_image: xcode10
+      osx_image: xcode11
       compiler: clang
       env:
         - MATRIX_EVAL="CC=clang && CXX=clang++ && export PATH=\"/usr/local/opt/llvm/bin:$PATH\" && export LDFLAGS=\"-L/usr/local/opt/llvm/lib\" && export CPPFLAGS=\"-I/usr/local/opt/llvm/include\""
@@ -255,7 +255,7 @@ matrix:
           - clinfo
     # GCC
     - os: osx
-      osx_image: xcode10
+      osx_image: xcode11
       compiler: gcc
       cache:
         ccache: true