fix(constellation): start Sagittarius on Nov 23 - #391

IsSagittarius is true on November 22, the last day of Scorpio:

if month == 11 && day >= 22 {

The table at the top of constellation.go has Scorpio as 10/24 to 11/22 and Sagittarius as 11/23 to 12/21, and IsScorpio already uses day <= 22. So on 22 November IsScorpio and IsSagittarius are both true, while Constellation() returns Scorpio. The existing Scorpio test already asserts that 2020-11-22 is Scorpio.

This changes the comparison to day >= 23 and adds s.False(Parse("2020-11-22").IsSagittarius()) to the existing valid carbon case.

I couldn't run Go locally, so I ran the suite on a fork:

• Test only, without the fix: test fails on macOS at constellation_unit_test.go:351 (TestConstellationSuite/TestCarbon_IsSagittarius/valid_carbon). The ubuntu and windows jobs of that run were cancelled after the macOS failure, so they didn't report a result.
• Test with the fix: test passes on ubuntu, macOS and windows, and lint passes.

The commit in this PR is the squashed form of the fix branch (identical tree).