gst-plugins-bad: add openssl depends for head build

This is for solving build error for adding dtls plugin.

Closes Homebrew/homebrew#37833.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Formula/gst-plugins-bad.rb

@@ -18,6 +18,7 @@ class GstPluginsBad < Formula
     depends_on "autoconf" => :build
     depends_on "automake" => :build
     depends_on "libtool" => :build
+    depends_on "openssl"
   end
 
   depends_on 'pkg-config' => :build