[gitg] libgitg-ext/meson.build: Use python module instead of deprecated python3 module

[Alberto Fanjul <albfan src gnome org>]

commit b411949ba349a7b139f330c80eab826e958076a7
Author: Pierre Lejeune <superheron gmail com>
Date:   Sat Feb 9 16:57:26 2019 +0100

    libgitg-ext/meson.build: Use python module instead of deprecated python3 module

 libgitg-ext/meson.build | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/libgitg-ext/meson.build b/libgitg-ext/meson.build
index f116ba01..cb2bebe2 100644
--- a/libgitg-ext/meson.build
+++ b/libgitg-ext/meson.build
@@ -125,10 +125,11 @@ custom_target(
 
 enable_python = get_option('python')
 if enable_python
-  python = import('python3')
+  pymod = import('python')
+  py_installation = pymod.find_installation('python3')
 
   install_data(
     'GitgExt.py',
-    install_dir: join_paths(python.sysconfig_path('purelib'), 'gi', 'overrides'),
+    install_dir: join_paths(py_installation.get_path('purelib'), 'gi', 'overrides'),
   )
 endif