sysutils/conky{-awesome}: update to 1.21.3

ChangeLog: https://github.com/brndnmtthws/conky/releases/tag/v1.21.3

Bug fixes

 * Replace strncat with strcat
 * Fix minimum height not being applied
 * Revert removal of dpi scaling
 * Fix for the graph scale text colour changing depending on graph position
 * Restore previous strut behavior

Miscellaneous

 * Bump version
 * Docker: make sure image has sensible default name
 * Docker: only write to cache if creds available
 * Docker cache extern pr
 * build(deps): bump the actions group with 2 updates