Update HetrickCV.json (#129)

Added Linux builds

plugins/HetrickCV.json

@@ -15,6 +15,10 @@
     "mac": {
       "download": "https://github.com/mhetrick/hetrickcv/releases/download/0.5.4/HetrickCV-0.5.4-mac.zip",
       "sha256": "5e8ef433ee03c30fa0a46699c60a2293868b458a0e60aeae7964091e6f8c4342"
+    },
+    "lin": {
+      "download": "https://github.com/mhetrick/hetrickcv/releases/download/0.5.4/HetrickCV-0.5.4-lin.zip",
+      "sha256": "a445990de47f31304d33ce1f6f10e35b9d28536cee9b77f8c1a27e545e4fb892"
     }
   }
 }