crystal-lang: remove gmp dependency

gmp was not even linked and system pcre works fine

Closes #19176.

Signed-off-by: ilovezfs <ilovezfs@icloud.com>

Formula/crystal-lang.rb

@@ -1,7 +1,7 @@
 class CrystalLang < Formula
   desc "Fast and statically typed, compiled language with Ruby-like syntax"
   homepage "https://crystal-lang.org/"
-  revision 1
+  revision 2
 
   stable do
     url "https://github.com/crystal-lang/crystal/archive/0.23.1.tar.gz"
@@ -37,7 +37,6 @@ class CrystalLang < Formula
   depends_on "bdw-gc"
   depends_on "llvm@4"
   depends_on "pcre"
-  depends_on "gmp"
   depends_on "libyaml" if build.with? "shards"
 
   resource "boot" do