relnotes: add 6.0.3 stable

relnotes: add 6.0.3

Differential Revision: https://phab.mercurial-scm.org/D12204

--- a/relnotes/6.0	Fri Feb 18 12:51:23 2022 +0100
+++ b/relnotes/6.0	Fri Feb 18 13:14:32 2022 +0100
@@ -1,3 +1,11 @@
+= Mercurial 6.0.3 =
+
+  * Fix an infinite loop in edge cases of the pure Python dirstate-v2 packer
+  * Fix a small race condition with deleted files in Rust-augmented status
+  * Small improvement to Python 3.11 compatibility
+  * Fixed some typos in help messages that caused missing sections
+  * Centos -> Rockylinux packaging
+
 = Mercurial 6.0.2 =
 
   * Fix `hg incoming` and `hg outgoing` with remote subrepos on Windows