ci: enable unittests on macos-14

Add more filters so that LuaJIT can parse headers on macOS 14.

The system headers use a style of enum introduced in C++11 (and allowed
as an extension in C by clang) of the form:

    enum Name : Type {

The system headers also use bitfields in the mach_vm_range_recipe* types:

    struct Foo { int bar : 32; }

Neither of these constructs can be parsed by LuaJIT, so filter the lines
out. Neither of these declarations are used by neovim's unittests.

There is a (now closed) issue about bitfields for LuaJIT:

    https://github.com/LuaJIT/LuaJIT/issues/951

Fixes #26145.

.github/workflows/test.yml

@@ -114,8 +114,6 @@ jobs:
             build: { flavor: tsan }
           - test: unittest
             build: { flavor: puc-lua }
-          - test: unittest
-            build: { runner: macos-14 } # unittests don't work on M1 #26145
           - test: oldtest
             build: { flavor: tsan }
     runs-on: ${{ matrix.build.runner }}