[clang] README.txt: Replace the link to the old bug tracker with the new one. (#93878)

Author: Eclips4

clang/README.txt

@@ -23,4 +23,4 @@ on the Clang forums:
   https://discourse.llvm.org/c/clang/
 
 If you find a bug in Clang, please file it in the LLVM bug tracker:
-  http://llvm.org/bugs/
+  https://github.com/llvm/llvm-project/issues