typo fix in #12017 (backport #12023)

[mergify]

fixed couplig to coupling

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This is an automatic backport of pull request #12023 done by Mergify.

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[coveralls]

Pull Request Test Coverage Report for Build 8310571059

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 5 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.01%) to 89.297%

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Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	93.81%
crates/qasm2/src/lex.rs	4	91.94%

Totals
Change from base Build 8310555580:	0.01%
Covered Lines:	58917
Relevant Lines:	65979

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💛 - Coveralls