all.bash: add mvdan.cc/unparam
all.bash: add mvdan.cc/unparam

Change-Id: Ie0090704380ffb3d7de0387c7d468d2922d82ee6
Reviewed-on: https://team-review.git.corp.google.com/c/golang/discovery/+/701078
Reviewed-by: Jonathan Amsterdam <e3d3698b2ccd5955e4adf250d0785062d0f9018b@google.com>

golang/pkgsite,golang/pkgsite,golang/pkgsite,golang/pkgsite