[libadwaita] Use project_source_root() instead of source_root()

[Alexander Mikhaylenko <alexm src gnome org>]

commit b46a45f9c13451274da6118303fd868fd15f03f4
Author: Tristan Partin <tristan partin io>
Date:   Thu Nov 4 13:06:21 2021 -0500

    Use project_source_root() instead of source_root()
    
    meson.source_root() is deprecated.

 src/meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/meson.build b/src/meson.build
index d03fa87d..6d3b5e7a 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -239,7 +239,7 @@ libadwaita_link_args = []
 libadwaita_symbols_file = 'libadwaita.syms'
 
 # Check linker flags
-ld_version_script_arg = '-Wl,--version-script,@0@/@1@'.format(meson.source_root(),
+ld_version_script_arg = '-Wl,--version-script,@0@/@1@'.format(meson.project_source_root(),
                                                               libadwaita_symbols_file)
 if cc.links('int main() { return 0; }', args : ld_version_script_arg, name : 'ld_supports_version_script')
   libadwaita_link_args += [ld_version_script_arg]