Bump version number from 10.8.1 to 10.9.0 #1246

Job	Run time
Documentation	1m 39s
Unit/Julia 1.3/ubuntu-latest/x64	9m 9s
Unit/Julia 1.4/ubuntu-latest/x64	9m 20s
Unit/Julia 1.5/ubuntu-latest/x64	8m 21s
Unit/Julia 1.6/ubuntu-latest/x64	7m 46s
Doctests	2m 19s
Unit/Julia 1.7/ubuntu-latest/x64	6m 19s
Unit/Julia 1.8/ubuntu-latest/x64	5m 44s
Unit/Julia 1/ubuntu-latest/x64	7m 41s
Unit/Julia nightly/ubuntu-latest/x64	7m 8s
	1h 5m 26s

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