Upgrade deepmerge

Still no esm but at least we got rid from umd wrapper here.

Details are here
TehShrike/deepmerge#155

packages/material-ui-styles/package.json

@@ -44,7 +44,7 @@
     "@material-ui/utils": "^4.1.0",
     "clsx": "^1.0.2",
     "csstype": "^2.5.2",
-    "deepmerge": "^3.0.0",
+    "deepmerge": "^4.0.0",
     "hoist-non-react-statics": "^3.2.1",
     "jss": "10.0.0-alpha.17",
     "jss-plugin-camel-case": "10.0.0-alpha.17",

packages/material-ui-system/package.json

@@ -39,7 +39,7 @@
   },
   "dependencies": {
     "@babel/runtime": "^7.2.0",
-    "deepmerge": "^3.0.0",
+    "deepmerge": "^4.0.0",
     "prop-types": "^15.7.2",
     "warning": "^4.0.1"
   },

packages/material-ui/package.json

@@ -45,7 +45,7 @@
     "@types/react-transition-group": "^2.0.16",
     "clsx": "^1.0.2",
     "convert-css-length": "^2.0.0",
-    "deepmerge": "^3.0.0",
+    "deepmerge": "^4.0.0",
     "hoist-non-react-statics": "^3.2.1",
     "is-plain-object": "^3.0.0",
     "normalize-scroll-left": "^0.2.0",

yarn.lock

@@ -5312,11 +5312,16 @@ deep-is@~0.1.3:
   resolved "https://registry.yarnpkg.com/deep-is/-/deep-is-0.1.3.tgz#b369d6fb5dbc13eecf524f91b070feedc357cf34"
   integrity sha1-s2nW+128E+7PUk+RsHD+7cNXzzQ=
 
-[email protected], deepmerge@^3.0.0:
+[email protected]:
   version "3.2.0"
   resolved "https://registry.yarnpkg.com/deepmerge/-/deepmerge-3.2.0.tgz#58ef463a57c08d376547f8869fdc5bcee957f44e"
   integrity sha512-6+LuZGU7QCNUnAJyX8cIrlzoEgggTM6B7mm+znKOX4t5ltluT9KLjN6g61ECMS0LTsLW7yDpNoxhix5FZcrIow==
 
+deepmerge@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/deepmerge/-/deepmerge-4.0.0.tgz#3e3110ca29205f120d7cb064960a39c3d2087c09"
+  integrity sha512-YZ1rOP5+kHor4hMAH+HRQnBQHg+wvS1un1hAOuIcxcBy0hzcUf6Jg2a1w65kpoOUnurOfZbERwjI1TfZxNjcww==
+
 default-require-extensions@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/default-require-extensions/-/default-require-extensions-2.0.0.tgz#f5f8fbb18a7d6d50b21f641f649ebb522cfe24f7"