chore: fix a type in a code comment

[hgsgtk]

Thank you for your great migration tool! It helps me lots everyday.

The commit fixes a small type in a code comment in sqlserver.go.

[coveralls]

Pull Request Test Coverage Report for Build 2067905493

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 57.807%

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Totals
Change from base Build 1997075650:	0.0%
Covered Lines:	3743
Relevant Lines:	6475

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💛 - Coveralls