checkbashisms: run under tainted mode (#26319)

It's not a universal solution but I think it'd work okay here, unless
I'm missing something.

Docs:
* http://perldoc.perl.org/perlglossary.html#tainted
* https://docstore.mik.ua/orelly/linux/cgi/ch08_04.htm

Closes https://github.com/Homebrew/homebrew-core/pull/26290.

Formula/checkbashisms.rb

@@ -10,7 +10,11 @@ class Checkbashisms < Formula
   bottle :unneeded
 
   def install
-    inreplace "scripts/checkbashisms.pl", "###VERSION###", version
+    inreplace "scripts/checkbashisms.pl" do |s|
+      s.gsub! "###VERSION###", version
+      s.gsub! "#!/usr/bin/perl", "#!/usr/bin/perl -T"
+    end
+
     bin.install "scripts/checkbashisms.pl" => "checkbashisms"
     man1.install "scripts/checkbashisms.1"
   end