Build images for tags matching vX.Y.Z - #627

these 2 derivations will be built:
  /nix/store/yn0cvc3gsv6y6mixr6q06jnv61r7lds3-install-agenix-shell.drv
  /nix/store/a6vg1abksckbj2p56n3n0xr03l9ipa18-nix-shell.drv
these 2 paths will be fetched (0.76 MiB download, 2.98 MiB unpacked):
  /nix/store/4dj6cw0vpw870zmg3vj7wm50jq7i48ij-psyche
  /nix/store/fxqm63nklh2sp1zw2ajfdajg7yq7md6j-psyche-python-env