[gi-docgen] Add test files to the source dist

[Emmanuele Bassi <ebassi src gnome org>]

commit cb84bd9fbfb3a8af0253fb0744cd4c36be7344c5
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Nov 10 00:19:21 2021 +0000

    Add test files to the source dist
    
    Otherwise they won't be picked up.

 MANIFEST.in | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/MANIFEST.in b/MANIFEST.in
index 9bd8ab3..c644e29 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: CC0-1.0
 
 include pyproject.toml
+include pytest.ini
 include README.md meson.build gi-docgen.pc.in
 include gi-docgen.py
 include .flake8
@@ -16,6 +17,8 @@ include docs/*.py
 include docs/Makefile
 include examples/*.js
 include examples/*.toml
+include test/*.py
 include meson_options.txt
 recursive-include docs *.rst
 recursive-include gidocgen/templates *
+recursive-include test/gir *