fix: remove unused rapidjson patch file

src/qt5/rapidjson-readonly-member-fix.patch

@@ -1,22 +0,0 @@
-From 3b2441b87f99ab65f37b141a7b548ebadb607b96 Mon Sep 17 00:00:00 2001
-From: Janusz Chorko <janusz.chorko@apdu.pl>
-Date: Fri, 26 Aug 2016 21:17:38 +0200
-Subject: [PATCH] Removed non-compiling assignment operator. Fixed #718
-
----
- include/rapidjson/document.h | 2 --
- 1 file changed, 2 deletions(-)
-
-diff --git a/include/rapidjson/document.h b/include/rapidjson/document.h
-index e3e20dfbd..b0f1f70be 100644
---- a/include/rapidjson/document.h
-+++ b/include/rapidjson/document.h
-@@ -316,8 +316,6 @@ struct GenericStringRef {
- 
-     GenericStringRef(const GenericStringRef& rhs) : s(rhs.s), length(rhs.length) {}
- 
--    GenericStringRef& operator=(const GenericStringRef& rhs) { s = rhs.s; length = rhs.length; }
--
-     //! implicit conversion to plain CharType pointer
-     operator const Ch *() const { return s; }
-