Description: update doc for sphinx4
Forwarded: https://github.com/AdaCore/gprbuild/pull/90
Author: Nicolas Boulenguez <nicolas@debian.org>

--- a/doc/share/conf.py
+++ b/doc/share/conf.py
@@ -96,5 +96,5 @@
 
 
 def setup(app):
-    app.add_lexer('ada', ada_pygments.AdaLexer())
-    app.add_lexer('gpr', ada_pygments.GNATProjectLexer())
+    app.add_lexer('ada', ada_pygments.AdaLexer)
+    app.add_lexer('gpr', ada_pygments.GNATProjectLexer)