fix(AUR): Remove failing call to version.sh (#877)

version.sh is supposed to set the GIT_TAG macro in version.hpp to the
output of 'git describe ...', however it uses relative paths and can't
find 'include/version.hpp'

'include/CMakeLists.txt' already has the same functionality so this is
not needed

contrib/polybar-git.aur/PKGBUILD

@@ -35,9 +35,6 @@ prepare() {
 
 build() {
   cd "${_pkgname}/build" || exit 1
-  if [ -x ../common/version.sh ]; then
-    ../common/version.sh
-  fi
   cmake -DCMAKE_INSTALL_PREFIX=/usr ..
   cmake --build .
 }