[nongnu] elpa/swift-mode 94d687d 173/496: Add required ELPA source

[ELPA Syncer]

branch: elpa/swift-mode
commit 94d687d187868f8ff465c7f80e6553fbaf0cfa8a
Author: ap4y <lod@pisem.net>
Commit: ap4y <lod@pisem.net>

    Add required ELPA source
    
    flycheck requires "let-alist" package which was moved to ELPA. see
    https://github.com/flycheck/flycheck/issues/551
---
 Cask | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Cask b/Cask
index 5159dbb..01fa162 100644
--- a/Cask
+++ b/Cask
@@ -1,4 +1,5 @@
 (source melpa)
+(source gnu)
 (source org)
 
 (package-file "swift-mode.el")