Backport PR #19553 on branch v3.5.x (ENH: Adding callbacks to Norms for update signals)#20966

dstansby merged 1 commit intomatplotlib:v3.5.xmatplotlib/matplotlib:v3.5.xfrom

meeseeksmachine:auto-backport-of-pr-19553-on-v3.5.xmeeseeksmachine/matplotlib:auto-backport-of-pr-19553-on-v3.5.xCopy head branch name to clipboard