macOS rolling: don't need tinyxml (#4093)

This removes tinyxml from the list of brew dependencies
to install on rolling.

Signed-off-by: Steve Peters <[email protected]>

Author: scpeters

source/Installation/Alternatives/macOS-Development-Setup.rst

@@ -63,7 +63,7 @@ You need the following things installed to build ROS 2:
 
       brew install asio assimp bison bullet cmake console_bridge cppcheck \
         cunit eigen freetype graphviz opencv openssl orocos-kdl pcre poco \
-        pyqt5 python qt@5 sip spdlog tinyxml tinyxml2
+        pyqt5 python qt@5 sip spdlog tinyxml2
 
 #.
    Setup some environment variables: