tools: fix md5 hash for ICU 68.1 src

Correct md5sum hash for the tarball version of the ICU 68.1 source.
The previously recorded md5sum hash was for the zip version.

PR-URL: #36777
Fixes: #36776
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Beth Griggs <bgriggs@redhat.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>

tools/icu/current_ver.dep

@@ -1,6 +1,6 @@
 [
   {
     "url": "https://github.com/unicode-org/icu/releases/download/release-68-1/icu4c-68_1-src.tgz",
-    "md5": "fd03b2d916dcadd3711b4c4a100a1713"
+    "md5": "6a99b541ea01f271257b121a4433c7c0"
   }
 ]