resume hook: "invalid arithmetic operator" if SYSTEMD_COLORS=true

"resume" install script can't evaluate systemd version if SYSTEMD_COLORS=true is set in user's shell environment:

$ export SYSTEMD_COLORS=true
$ mkinitcpio 
==> Starting dry run: '6.12.7-arch1-1'
  -> Running build hook: [base]
  -> Running build hook: [udev]
  -> Running build hook: [autodetect]
  -> Running build hook: [microcode]
  -> Running build hook: [modconf]
  -> Running build hook: [kms]
  -> Running build hook: [keyboard]
  -> Running build hook: [keymap]
  -> Running build hook: [consolefont]
  -> Running build hook: [block]
  -> Running build hook: [encrypt]
==> WARNING: Possibly missing firmware for module: 'qat_420xx'
  -> Running build hook: [partprobe-encrypt]
  -> Running build hook: [filesystems]
  -> Running build hook: [resume]
/usr/lib/initcpio/install/resume: line 11: ((: 257: syntax error: invalid arithmetic operator (error token is "")
  -> Running build hook: [fsck]
==> Generating module dependencies
==> Dry run complete, use -g IMAGE to generate a real image

Note error message after running "resume" hook.