News entry for 1.21 release

Author: insertinterestingnamehere

NEWS

@@ -1,4 +1,20 @@
---- 1.20 (current) ---
+--- 1.21 ---
+Improvements:
+- Support and testing for clang 19 and gcc 14
+- Partial support for thread sanitizer
+- Dramatically simplified build system
+- Removed numerous unused build configs
+- Fixed a minor performance regression from the last release
+- Removed hand-imlemented atomics in favor of C11 atomics and existing intrinsics
+- Removed unmaintained support for eurekas
+- Removed unmaintained support for distributed Qthreads
+- Removed various unmaintained debugging and profiling code paths
+- Dropped support for numerous compilers that no are no longer available
+- Dropped support for various unmaintained architectures like Tilera, Itanium, Alpha, MIPS, and Sparc
+- Dropped support for various OS configs that we don't test like Solaris, HPUX, and AIX
+- Removed several unmaintained/untested threadqueue and topology detection options
+
+--- 1.20 ---
 Improvements:
  - Improve and expand CI testing
  - Fix compilation and testing for an expanded range of platforms, compilers, and operating systems