fix: update SFR diversion flow to zero when its upstream downflow is zero

[ougx]

No description provided.

[emorway-usgs]

@ougx, I should've caught this earlier, but would you mind updating the release notes to include a brief summary of your fix? You will find a .tex document called "develop.tex" located here: ..\modflow6.git\doc\ReleaseNotes. Under the heading ADVANCED STRESS PACKAGES, it would be helpful to add a new \item that describes the behavior that was happening and what the expected behavior is, and what the fix does to resolve the issue.

[jdhughes-usgs]

This PR is going to have to be rebased against develop if PR #1464 is merged before this one.

[jdhughes-usgs]

@ougx, I should've caught this earlier, but would you mind updating the release notes to include a brief summary of your fix? You will find a .tex document called "develop.tex" located here: ..\modflow6.git\doc\ReleaseNotes. Under the heading ADVANCED STRESS PACKAGES, it would be helpful to add a new \item that describes the behavior that was happening and what the expected behavior is, and what the fix does to resolve the issue.

The fix should be added at

modflow6/doc/ReleaseNotes/develop.tex

Line 47 in 1783084

% \item xxx