icu: Bump default version from 74 to 76

doc/release-notes/rl-2505.section.md

@@ -12,6 +12,8 @@
   It should generally be replaced with `rustPlatform.fetchCargoVendor`, but `rustPlatform.importCargoLock` may also be appropriate in some circumstances.
   `rustPlatform.buildRustPackage` users must set `useFetchCargoVendor` to `true` and regenerate the `cargoHash`.
 
+- Default ICU version updated from 74 to 76
+
 <!-- To avoid merge conflicts, consider adding your item at an arbitrary place in the list instead. -->
 
 ### Titanium removed {#sec-nixpkgs-release-25.05-incompatibilities-titanium-removed}

pkgs/top-level/all-packages.nix

@@ -9269,7 +9269,7 @@ with pkgs;
   #
   # `icuReal` is provided in case the upstream icu package is needed on Darwin instead of the fork.
   # Note that the versioned icu packages always correspond to the upstream versions.
-  icuReal = icu74;
+  icuReal = icu76;
   icu = if stdenv.hostPlatform.isDarwin then darwin.ICU else icuReal;
 
   idasen = with python3Packages; toPythonApplication idasen;