gh-39278: Meson: build groups even without gap
    
`group.pyx` compiles fine also without gap installed.

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URL: #39278
Reported by: Tobias Diez
Reviewer(s): Dima Pasechnik

Author: Release Manager

src/sage/groups/meson.build

@@ -38,13 +38,17 @@ extension_data = {
 }
 
 foreach name, pyx : extension_data
+  deps = [py_dep, gmp]
+  if name == 'libgap_wrapper'
+    deps += [gap]
+  endif
   py.extension_module(
     name,
     sources: pyx,
     subdir: 'sage/groups',
     install: true,
     include_directories: [inc_cpython],
-    dependencies: [py_dep, gmp, gap],
+    dependencies: deps,
   )
 endforeach