Require seq and subr-x for Emacs <28 compatibility

seq-find and string-trim-right are not globally available in
Emacs 26–27 and need explicit requires. This fixes CI failures
on those versions.

Author: jaeyeom

eshell-command-not-found.el

@@ -48,6 +48,8 @@
 ;;; Code:
 
 (require 'esh-ext)
+(require 'seq)
+(require 'subr-x)
 
 ;;;###autoload
 (defcustom eshell-command-not-found-command