meson: Replace deprecated source_root with project_source_root

Author: ryonakano

platform-data/data/meson.build

@@ -1,7 +1,7 @@
 i18n.merge_file(
     input: 'platform.appdata.xml.in',
     output: 'io.elementary.Platform.appdata.xml',
-    po_dir: join_paths(meson.source_root(), 'po'),
+    po_dir: join_paths(meson.project_source_root(), 'po'),
     type: 'xml',
     install: true,
     install_dir: join_paths(get_option('datadir'), 'metainfo'),
@@ -10,7 +10,7 @@ i18n.merge_file(
 i18n.merge_file(
     input: 'sdk.appdata.xml.in',
     output: 'io.elementary.Sdk.appdata.xml',
-    po_dir: join_paths(meson.source_root(), 'po'),
+    po_dir: join_paths(meson.project_source_root(), 'po'),
     type: 'xml',
     install: true,
     install_dir: join_paths(get_option('datadir'), 'metainfo'),

platform-data/meson.build

@@ -1,5 +1,6 @@
 project(
-    'io.elementary.Platform.Data'
+    'io.elementary.Platform.Data',
+    meson_version: '>= 0.56.0'
 )
 
 i18n = import('i18n')

platform-data/po/meson.build

@@ -1,5 +1,5 @@
 i18n.gettext('extra',
-    args: '--directory=' + meson.source_root(),
+    args: '--directory=' + meson.project_source_root(),
     preset: 'glib',
     install: false
 )