Force at least one classical bit in qpd_measurements register

[garrison]

Fixes #564

This is a potential workaround to openqasm/qe-qasm#37

[coveralls]

Pull Request Test Coverage Report for Build 8825413156

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 95.484%

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Totals
Change from base Build 8821415721:	0.0%
Covered Lines:	3489
Relevant Lines:	3654

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💛 - Coveralls

[caleb-johnson]

Looks great. Should probably add a release note

(EDIT): Just saw this is still in draft :)

[caleb-johnson]

Thanks for the quick fix