goplus: test fix

[stefanb]

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
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Test failure noticed in

• go 1.24.0, go@1.23 1.23.6 (new formula) #201070

but pinning to go1.23 made no difference.

Not sure why it passed in previous runs on same version

• goplus: update 1.2.6 bottle. #187839
• goplus 1.2.6 #168867

Not the first upstream stdout/stderr inconsistency / wierdness:

• Inconsistent command line output for gop help and gop help run goplus/gop#496
• fix inconsistent command line output for different help info goplus/gop#497