Remove dependency on dash

As of assess v0.4, it's using seq rather than dash:
phillord/assess@deb6e4c

Author: wasamasa

Eask

@@ -11,7 +11,6 @@
 
 (development
  (depends-on "assess")
- (depends-on "dash")
  (depends-on "m-buffer"))
 
 (setq network-security-level 'low)  ; see https://github.com/jcs090218/setup-emacs-windows/issues/156#issuecomment-932956432

csharp-mode-tests.el

@@ -34,9 +34,7 @@
   (setq package-check-signature nil)
   (setq network-security-level 'low)  ; see https://github.com/jcs090218/setup-emacs-windows/issues/156#issuecomment-932956432
 
-  ;; assess depends on dash 2.12.1, which is no longer available
-  ;; installing dash, resolves 2.13.0, and fixes this broken dependency.
-  (dolist (p '(dash assess))
+  (dolist (p '(assess))
     (when (not (package-installed-p p))
       (package-refresh-contents)
       (package-install p))))