Fix version and date in CHANGELOG.md

[MaxDesiatov]

The changes for the previous version were mistakenly attributed to 0.5.0, while actually they belong to 0.6.0. The release date is fixed as well.

[github-actions]

Time Change: -58.5ms (0%)

Total Time: 13,139.5ms

ℹ️ View Unchanged

Test name	Duration	Change
Serialization/Write JavaScript number directly	182.5ms	+6.5ms (3%)
Serialization/Write JavaScript string directly	181ms	-2.5ms (1%)
Serialization/Swift Int to JavaScript	4,749ms	-58.5ms (1%)
Serialization/Swift String to JavaScript	4,885.5ms	-45ms (0%)
Object heap/Increment and decrement RC	3,141.5ms	+41ms (1%)

_{performance-action}