The backend does not require a mesonbuild module for every flavor.
the `meson` command from the regular RPM package is sufficient.

Index: meson_python-0.12.0/pyproject.toml
===================================================================
--- meson_python-0.12.0.orig/pyproject.toml
+++ meson_python-0.12.0/pyproject.toml
@@ -2,7 +2,6 @@
 build-backend = 'mesonpy'
 backend-path = ['.']
 requires = [
-  'meson>=0.63.3',
   'pyproject-metadata>=0.6.1',
   'tomli>=1.0.0; python_version<"3.11"',
   'typing-extensions>=3.7.4; python_version<"3.10"',
@@ -25,7 +24,6 @@ classifiers = [
 
 dependencies = [
   'colorama; os_name == "nt"',
-  'meson>=0.63.3',
   'pyproject-metadata>=0.6.1', # not a hard dependency, only needed for projects that use PEP 621 metadata
   'tomli>=1.0.0; python_version<"3.11"',
   'typing-extensions>=3.7.4; python_version<"3.10"',