Update dependency gulp-clean-css to v3.9.4

package-lock.json

@@ -1819,7 +1819,7 @@
       "resolved": "https://registry.npmjs.org/clean-css/-/clean-css-4.1.11.tgz",
       "integrity": "sha1-Ls3xRaujj1R0DybO/Q/z4D4SXWo=",
       "requires": {
-        "source-map": "0.5.7"
+        "source-map": "0.5.x"
       }
     },
     "cli-cursor": {
@@ -4957,9 +4957,9 @@
       }
     },
     "gulp-clean-css": {
-      "version": "3.9.3",
-      "resolved": "https://registry.npmjs.org/gulp-clean-css/-/gulp-clean-css-3.9.3.tgz",
-      "integrity": "sha512-mw5Qrio7W3rvswmVlZ7eaxOhBIp6zQMBFLgcHoi/xbOtaKT5zmElkHt8mvbRre7fMt5eLgppIkW+j9Cm+O/UqQ==",
+      "version": "3.9.4",
+      "resolved": "https://registry.npmjs.org/gulp-clean-css/-/gulp-clean-css-3.9.4.tgz",
+      "integrity": "sha512-jsbAj65WM08H1jCFOKpIvA1OlACk7OHS2FFTeeBZrSJ5OR1PJzAqi0I2R2LTWYN3oMd/N1JYN9cN2IS/8eYqdg==",
       "requires": {
         "clean-css": "4.1.11",
         "plugin-error": "1.0.1",
@@ -4977,8 +4977,8 @@
           "resolved": "https://registry.npmjs.org/extend-shallow/-/extend-shallow-3.0.2.tgz",
           "integrity": "sha1-Jqcarwc7OfshJxcnRhMcJwQCjbg=",
           "requires": {
-            "assign-symbols": "1.0.0",
-            "is-extendable": "1.0.1"
+            "assign-symbols": "^1.0.0",
+            "is-extendable": "^1.0.1"
           }
         },
         "is-extendable": {
@@ -4986,7 +4986,7 @@
           "resolved": "https://registry.npmjs.org/is-extendable/-/is-extendable-1.0.1.tgz",
           "integrity": "sha512-arnXMxT1hhoKo9k1LZdmlNyJdDDfy2v0fXjFlmok4+i8ul/6WlbVge9bhM74OpNPQPMGUToDtz+KXa1PneJxOA==",
           "requires": {
-            "is-plain-object": "2.0.4"
+            "is-plain-object": "^2.0.4"
           }
         },
         "plugin-error": {
@@ -4994,10 +4994,10 @@
           "resolved": "https://registry.npmjs.org/plugin-error/-/plugin-error-1.0.1.tgz",
           "integrity": "sha512-L1zP0dk7vGweZME2i+EeakvUNqSrdiI3F91TwEoYiGrAfUXmVv6fJIq4g82PAXxNsWOp0J7ZqQy/3Szz0ajTxA==",
           "requires": {
-            "ansi-colors": "1.0.1",
-            "arr-diff": "4.0.0",
-            "arr-union": "3.1.0",
-            "extend-shallow": "3.0.2"
+            "ansi-colors": "^1.0.1",
+            "arr-diff": "^4.0.0",
+            "arr-union": "^3.1.0",
+            "extend-shallow": "^3.0.2"
           }
         }
       }

package.json

@@ -25,7 +25,7 @@
     "eslint-plugin-react": "7.7.0",
     "gulp": "3.9.1",
     "gulp-autoprefixer": "5.0.0",
-    "gulp-clean-css": "3.9.3",
+    "gulp-clean-css": "3.9.4",
     "gulp-concat": "2.6.1",
     "gulp-eslint": "4.0.2",
     "gulp-jest": "4.0.2",