Adds support for PostgreSQL "END"

[tobyhede]

Related to #1034

Adds support for treating END as COMMIT.
END is still used as a statement delimiter, but we only check this case if expecting a statement to end.

I am not 100% sure this is the right approach, but the tests pass.

[coveralls]

Pull Request Test Coverage Report for Build 6938222562

• 7 of 8 (87.5%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.001%) to 87.706%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/parser/mod.rs	6	7	85.71%

Files with Coverage Reduction	New Missed Lines	%
src/parser/mod.rs	1	83.22%

Totals
Change from base Build 6937704001:	-0.001%
Covered Lines:	17900
Relevant Lines:	20409

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💛 - Coveralls

[alamb]

Thank you for the contribution @tobyhede 🙏

[alamb]

Thanks again @tobyhede