Update dev dependencies.

paragonie-security · paragonie-security · commit eccf915f45f9 · 2018-03-10T14:47:49.000-05:00
diff --git a/composer.json b/composer.json
@@ -29,8 +29,8 @@
     "php": "^7"
   },
   "require-dev": {
-    "phpunit/phpunit": "^6",
-    "vimeo/psalm": "^0.3|^1"
+    "phpunit/phpunit": "^6|^7",
+    "vimeo/psalm": "^1"
   },
   "autoload": {
     "psr-4": {
