Extra specs for String#append_as_bytes #1880

Job	Run time
specs (ubuntu, 3.0.6)	1m 36s
specs (ubuntu, 3.0.6)	1m 36s
specs (ubuntu, 3.1.4)	1m 27s
specs (ubuntu, 3.1.4)	1m 27s
RuboCop	30s
RuboCop	30s
specs (ubuntu, 3.2.2)	1m 27s
specs (ubuntu, 3.2.2)	1m 27s
specs (ubuntu, 3.3.0)	57s
specs (ubuntu, 3.3.0)	1m 27s
specs (ubuntu, 3.4.1)	1m 37s
specs (ubuntu, 3.4.1)	1m 37s
specs (macos, 3.0.6)	1m 18s
specs (macos, 3.0.6)	1m 18s
specs (macos, 3.1.4)	1m 20s
specs (macos, 3.1.4)	1m 20s
specs (macos, 3.2.2)	1m 8s
specs (macos, 3.2.2)	1m 8s
specs (macos, 3.3.0)	55s
specs (macos, 3.3.0)	1m 9s
specs (macos, 3.4.1)	1m 11s
specs (macos, 3.4.1)	1m 11s
specs (windows, 3.0.6)	4m 56s
specs (windows, 3.0.6)	4m 56s
specs (windows, 3.1.4)	6m 4s
specs (windows, 3.1.4)	6m 4s
specs (windows, 3.2.2)	5m 22s
specs (windows, 3.2.2)	5m 22s
specs (windows, 3.3.0)	5m 18s
specs (windows, 3.3.0)	5m 18s
specs (windows, 3.4.1)	5m 15s
specs (windows, 3.4.1)	5m 15s
specs (ubuntu, 3.3.0, --enable-frozen-string-literal)	1m 23s
specs (ubuntu, 3.3.0, --enable-frozen-string-literal)	1m 23s
	1h 24m 12s

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