Add patch to fix Qt4 backends.

python-matplotlib.spec

@@ -52,6 +52,8 @@ Source1:        setup.cfg
 # Because the qhull package stopped shipping pkgconfig files.
 # https://src.fedoraproject.org/rpms/qhull/pull-request/1
 Patch0001:      0001-Force-using-system-qhull.patch
+# https://github.com/matplotlib/matplotlib/pull/12157
+Patch0002:      12157.patch
 
 # Fedora-specific patches; see:
 # https://github.com/QuLogic/matplotlib/tree/fedora-patches
@@ -240,6 +242,7 @@ Requires:       python3-matplotlib%{?_isa} = %{version}-%{release}
 %prep
 %autosetup -n matplotlib-%{version}%{?rctag} -N
 %patch0001 -p1
+%patch0002 -p1
 
 # Fedora-specific patches follow:
 %patch1001 -p1