Update 0.3.1 release date inCHANGELOG.md #290

Job	Run time
3.7 CH=23.8.4.69	57s
3.7 CH=22.5.1.2079	59s
3.7 CH=19.3.5	54s
3.7 CH=18.14.9	55s
3.8 CH=23.8.4.69	37s
3.8 CH=22.5.1.2079	37s
3.8 CH=19.3.5	37s
3.8 CH=18.14.9	34s
3.9 CH=23.8.4.69	58s
3.9 CH=22.5.1.2079	38s
3.9 CH=19.3.5	33s
3.9 CH=18.14.9	28s
3.10 CH=23.8.4.69	43s
3.10 CH=22.5.1.2079	38s
3.10 CH=19.3.5	28s
3.10 CH=18.14.9	30s
3.11 CH=23.8.4.69	36s
3.11 CH=22.5.1.2079	33s
3.11 CH=19.3.5	30s
3.11 CH=18.14.9	25s
3.12 CH=23.8.4.69	54s
3.12 CH=22.5.1.2079	55s
3.12 CH=19.3.5	53s
3.12 CH=18.14.9	51s
Indicate completion to coveralls.io	9s
	16m 52s

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