[gi-docgen] Add pyproject.toml to the manifest

[Emmanuele Bassi <ebassi src gnome org>]

commit 958d64ff9fba750d8dc7476d7a7e645c56e9bbc1
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Thu Apr 15 15:03:25 2021 +0100

    Add pyproject.toml to the manifest

 MANIFEST.in | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/MANIFEST.in b/MANIFEST.in
index c420ea8..8cdb69c 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,6 +1,7 @@
 # SPDX-FileCopyrightText: 2021  GNOME Foundation
 # SPDX-License-Identifier: CC0-1.0
 
+include pyproject.toml
 include README.md meson.build gi-docgen.pc.in
 include gi-docgen.py
 include .flake8