fix: restore cordova-ios engine requirement (#339)

diff --git a/package-lock.json b/package-lock.json
index 587c419..e9d3410 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -13,6 +13,9 @@
       },
       "engines": {
         "cordovaDependencies": {
+          "<6.0.0": {
+            "cordova-ios": "<6.0.0"
+          },
           ">=4.0.0": {
             "cordova-android": ">=3.6.0",
             "cordova-windows": ">=4.4.0"
diff --git a/package.json b/package.json
index cf24931..bd112b7 100644
--- a/package.json
+++ b/package.json
@@ -34,6 +34,9 @@
         "cordova-android": ">=3.6.0",
         "cordova-windows": ">=4.4.0"
       },
+      "<6.0.0": {
+        "cordova-ios": "<6.0.0"
+      },
       "6.0.2": {
         "cordova-android": ">=3.6.0 <11.0.0",
         "cordova-windows": ">=4.4.0"