TextEditor: Pledge "thread" since it's needed by GUI::FilePicker

This is a little bit awkward since it's only used for generating
thumbnails on a background thread and it's not like I care about
thumbnails very much in a text editor, but for now let's just pledge
"thread" so I can get on with the thing I wanted to get on with.

Applications/TextEditor/main.cpp

@@ -30,14 +30,14 @@
 
 int main(int argc, char** argv)
 {
-    if (pledge("stdio rpath accept cpath wpath shared_buffer unix fattr", nullptr) < 0) {
+    if (pledge("stdio thread rpath accept cpath wpath shared_buffer unix fattr", nullptr) < 0) {
         perror("pledge");
         return 1;
     }
 
     GUI::Application app(argc, argv);
 
-    if (pledge("stdio rpath accept cpath wpath shared_buffer", nullptr) < 0) {
+    if (pledge("stdio thread rpath accept cpath wpath shared_buffer", nullptr) < 0) {
         perror("pledge");
         return 1;
     }