add announcement for new GCC/Clang default versions

Author: h-vetinari

news/2025-07-01-moving-to-gcc-14-clang-19.md

@@ -0,0 +1,6 @@
+# Moving to GCC 14 and Clang 19 as default compiler versions
+
+As part of our regular toolchain updates, we're planning to update the default
+versions of GCC (for linux) to v14 and of Clang (for OSX) to v19, in one week.
+
+For more details, see https://github.com/conda-forge/conda-forge-pinning-feedstock/pull/7421.