Bump rexml from 3.3.4 to 3.3.6 #2542

Job	Run time
pod-lib-lint (ios, macos-14)	6m 53s
pod-lib-lint (ios, macos-13)	8m 50s
spm (iOS, macos-13)	5m 39s
pod-lib-lint (tvos, macos-14)	2m 31s
spm (iOS, macos-14)	8m 39s
pod-lib-lint (tvos, macos-13)	5m 36s
spm (tvOS, macos-13)	4m 34s
pod-lib-lint (macos --skip-tests, macos-14)	2m 17s
spm (tvOS, macos-14)	5m 49s
pod-lib-lint (macos --skip-tests, macos-13)	3m 10s
spm (macOS, macos-13)	2m 16s
pod-lib-lint (watchos, macos-14)	1m 44s
spm (macOS, macos-14)	5m 44s
spm (catalyst, macos-13)	2m 30s
pod-lib-lint (watchos, macos-13)	1m 51s
catalyst	2m 18s
spm (catalyst, macos-14)	4m 47s
spm (watchOS, macos-13)	4m 3s
spm (watchOS, macos-14)	6m 21s
quickstart	1m 33s
spm (macos-14, visionOS, Xcode_15.2)	6m 0s
quickstart-ftl-cron-only	0s
abtesting-cron-only	0s
	1h 33m 5s

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