Update rexml to 3.3.9 #11328

Job	Run time
lint_node	41s
Ruby 3.1 on ubuntu-latest	14m 36s
build_node (ubuntu-latest)	1m 25s
Ruby 3.2 on ubuntu-latest	14m 27s
lint_ruby	24s
build_node (macos-latest)	1m 57s
Ruby 3.3 on ubuntu-latest	11m 11s
spelling	18s
build_node (windows-latest)	7m 49s
Ruby 3.1 on macos-latest	10m 35s
Ruby 3.2 on macos-latest	9m 32s
Verify Jekyll website builds	11s
Ruby 3.3 on macos-latest	7m 2s
Ruby 3.1 on windows-latest	20m 59s
Ruby 3.2 on windows-latest	21m 32s
Ruby 3.3 on windows-latest	22m 5s
	2h 24m 44s

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