Add license for string processing #1333

Job	Run time
Lint	2m 28s
Build on limited environment	48s
Coverage	56s
Benchmark	3m 54s
Test (ubuntu-latest, 1.19)	1m 19s
Test (ubuntu-latest, 1.20)	1m 54s
Test (ubuntu-latest, 1.21)	2m 11s
Test (macos-latest, 1.19)	1m 28s
Test (macos-latest, 1.20)	1m 47s
Test (macos-latest, 1.21)	1m 29s
Test (windows-latest, 1.19)	3m 7s
Test (windows-latest, 1.20)	3m 27s
Test (windows-latest, 1.21)	3m 58s
	28m 46s

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