Add specs for Queue#freeze and SizedQueue#freeze #270

Job	Run time
RuboCop	27s
specs (ubuntu, 3.0.6)	1m 30s
specs (ubuntu, 3.1.4)	1m 33s
specs (ubuntu, 3.2.2)	1m 25s
specs (ubuntu, 3.3.0)	1m 25s
specs (macos, 3.0.6)	1m 56s
specs (macos, 3.1.4)	1m 24s
specs (macos, 3.2.2)	1m 28s
specs (macos, 3.3.0)	1m 31s
specs (windows, 3.0.6)	4m 14s
specs (windows, 3.1.4)	4m 57s
specs (windows, 3.2.2)	4m 52s
specs (windows, 3.3.0)	4m 0s
specs (ubuntu, 3.3.0, --enable-frozen-string-literal)	1m 31s
	32m 13s

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