Use more accurate qnorm value from R 4.3.0 (Closes #1251)

[eddelbuettel]

R-devel, per the Feb 4 NEWS post, now have a more accurate qnorm. We need to reflect that in a test.

There may a 'timing' issue with the docker container used for r-devel, but if this fails now I will update the container. The new tests passes locally.

Checklist

• Code compiles correctly
• R CMD check still passes all tests
• Prefereably, new tests were added which fail without the change
• Document the changes by file in ChangeLog

[Enchufa2]

LGTM. Alternatively, we could set e.g. a tolerance=0.0005 and call it a day. But this is fine too.