fix brew warning in CI. (#1431)

github hosted mac runners include ninja.

Author: tsteven4

.github/workflows/macos.yml

@@ -89,7 +89,6 @@ jobs:
         brew list -1 | grep python | while read formula; do brew unlink $formula; brew link --overwrite $formula; done
         brew list -1 | grep python
         ls -l $(brew --prefix)/bin | grep -i python
-        brew install ninja
         brew install docbook docbook-xsl fop gnu-sed
         # brew install is taking forever on macos-11, skip jing-trang and all it's dependencies.
         # jing 20241231 is failing with "Unknown XPath version 0", https://github.com/relaxng/jing-trang/issues/284