chore(maker-snap): upgrade electron-installer-snap to ^3.0.0

Only change: requires Node >= 6

package.json

@@ -156,7 +156,7 @@
     "electron-installer-dmg": "^2.0.0",
     "electron-installer-flatpak": "^0.8.0",
     "electron-installer-redhat": "^0.5.0",
-    "electron-installer-snap": "^2.0.0",
+    "electron-installer-snap": "^3.0.0",
     "electron-windows-store": "^0.12.0",
     "electron-winstaller": "^2.5.0",
     "electron-wix-msi": "^1.3.0"

packages/maker/snap/package.json

@@ -25,6 +25,6 @@
     "@electron-forge/shared-types": "6.0.0-beta.25"
   },
   "optionalDependencies": {
-    "electron-installer-snap": "^2.0.0"
+    "electron-installer-snap": "^3.0.0"
   }
 }

packages/publisher/snapcraft/package.json

@@ -23,6 +23,6 @@
     "fs-extra": "^5.0.0"
   },
   "optionalDependencies": {
-    "electron-installer-snap": "^2.0.0"
+    "electron-installer-snap": "^3.0.0"
   }
 }

yarn.lock

@@ -3194,9 +3194,9 @@ electron-installer-redhat@^0.5.0:
     word-wrap "^1.2.1"
     yargs "7.0.2"
 
-electron-installer-snap@^2.0.0:
-  version "2.0.0"
-  resolved "https://registry.yarnpkg.com/electron-installer-snap/-/electron-installer-snap-2.0.0.tgz#5346317b77bdd2f8373f8b9ba9128f743f48549b"
+electron-installer-snap@^3.0.0:
+  version "3.0.0"
+  resolved "https://registry.yarnpkg.com/electron-installer-snap/-/electron-installer-snap-3.0.0.tgz#d6285c858e8ebd8cd5c0d57a318e3bc39af2b745"
   dependencies:
     asar "^0.14.0"
     cross-spawn-promise "^0.10.1"
@@ -3209,6 +3209,7 @@ electron-installer-snap@^2.0.0:
     lodash.template "^4.4.0"
     nodeify "^1.0.1"
     pify "^3.0.0"
+    semver "^5.5.0"
     tmp-promise "^1.0.3"
     which "^1.3.0"
     yargs "^11.0.0"