Fix Cantera resource: remove incorrect revision hash

The revision hash for Cantera v3.1.0 was incorrect, causing build failure.
Remove the revision parameter and let Homebrew fetch the tag directly,
which will use the correct commit hash automatically.

Author: sbryngelson

packaging/homebrew/mfc.rb

@@ -25,8 +25,7 @@ class Mfc < Formula
 
   resource "cantera" do
     url "https://github.com/Cantera/cantera.git",
-        tag:      "v3.1.0",
-        revision: "3882f63dc48cc12bbc3cabb0c5c6e87e9bbaa8a0"
+        tag:      "v3.1.0"
   end
 
   def install