handle projects path with apostrophe (fixes #12691)

(cherry picked from commit b49b492)

Author: jef-n

src/app/qgisapp.cpp

@@ -9995,11 +9995,15 @@ void QgisApp::projectChanged( const QDomDocument &doc )
 
   QString expr;
   if ( !prevProjectDir.isNull() )
-    expr = QString( "sys.path.remove('%1'); " ).arg( prevProjectDir );
+  {
+    QString prev = prevProjectDir;
+    expr = QString( "sys.path.remove('%1'); " ).arg( prev.replace( "'", "\\'" ) );
+  }
 
   prevProjectDir = fi.canonicalPath();
 
-  expr += QString( "sys.path.append('%1')" ).arg( prevProjectDir );
+  QString prev = prevProjectDir;
+  expr += QString( "sys.path.append('%1')" ).arg( prev.replace( "'", "\\'" ) );
 
   QgsPythonRunner::run( expr );
 }