Bug 1763783 - Part 8: Bump minimum required ICU version to 71.1. r=platform-i18n-reviewers,jfkthame

Require at least 71.1 for `UNUM_APPROXIMATELY_SIGN_FIELD`.

Depends on D143280

Differential Revision: https://phabricator.services.mozilla.com/D143281

js/moz.configure

@@ -1104,7 +1104,7 @@ set_define(
 # ======================================================
 system_lib_option("--with-system-icu", help="Use system ICU")
 
-system_icu = pkg_check_modules("MOZ_ICU", "icu-i18n >= 70.1", when="--with-system-icu")
+system_icu = pkg_check_modules("MOZ_ICU", "icu-i18n >= 71.1", when="--with-system-icu")
 
 
 @depends("--with-system-icu")