fix(starters): update dependency prop-types to ^15.7.1 (gatsbyjs#11686)

package.json

@@ -13,7 +13,7 @@
     "gatsby-plugin-sharp": "^2.0.20",
     "gatsby-source-filesystem": "^2.0.20",
     "gatsby-transformer-sharp": "^2.1.13",
-    "prop-types": "^15.6.2",
+    "prop-types": "^15.7.1",
     "react": "^16.8.0",
     "react-dom": "^16.8.0",
     "react-helmet": "^5.2.0"

yarn.lock

@@ -6703,7 +6703,7 @@ longest@^1.0.0:
   resolved "https://registry.yarnpkg.com/longest/-/longest-1.0.1.tgz#30a0b2da38f73770e8294a0d22e6625ed77d0097"
   integrity sha1-MKCy2jj3N3DoKUoNIuZiXtd9AJc=
 
-loose-envify@^1.0.0, loose-envify@^1.1.0, loose-envify@^1.3.1, loose-envify@^1.4.0:
+loose-envify@^1.0.0, loose-envify@^1.1.0, loose-envify@^1.4.0:
   version "1.4.0"
   resolved "https://registry.yarnpkg.com/loose-envify/-/loose-envify-1.4.0.tgz#71ee51fa7be4caec1a63839f7e682d8132d30caf"
   integrity sha512-lyuxPGr/Wfhrlem2CL/UcnUc1zcqKAImBDzukY7Y5F/yQiNdko6+fRLevlw1HgMySw7f611UIY408EtxRSoK3Q==
@@ -8587,13 +8587,13 @@ promise@^7.1.1:
   dependencies:
     asap "~2.0.3"
 
-prop-types@^15.5.4, prop-types@^15.6.1, prop-types@^15.6.2:
-  version "15.6.2"
-  resolved "https://registry.yarnpkg.com/prop-types/-/prop-types-15.6.2.tgz#05d5ca77b4453e985d60fc7ff8c859094a497102"
-  integrity sha512-3pboPvLiWD7dkI3qf3KbUe6hKFKa52w+AE0VCqECtf+QHAKgOL37tTaNCnuX1nAAQ4ZhyP+kYVKf8rLmJ/feDQ==
+prop-types@^15.5.4, prop-types@^15.6.1, prop-types@^15.6.2, prop-types@^15.7.1:
+  version "15.7.1"
+  resolved "https://registry.yarnpkg.com/prop-types/-/prop-types-15.7.1.tgz#2fa61e0a699d428b40320127733ee2931f05d9d1"
+  integrity sha512-f8Lku2z9kERjOCcnDOPm68EBJAO2K00Q5mSgPAUE/gJuBgsYLbVy6owSrtcHj90zt8PvW+z0qaIIgsIhHOa1Qw==
   dependencies:
-    loose-envify "^1.3.1"
     object-assign "^4.1.1"
+    react-is "^16.8.1"
 
 proto-list@~1.2.1:
   version "1.2.4"
@@ -8845,6 +8845,11 @@ react-hot-loader@^4.6.2:
     shallowequal "^1.0.2"
     source-map "^0.7.3"
 
+react-is@^16.8.1:
+  version "16.8.1"
+  resolved "https://registry.yarnpkg.com/react-is/-/react-is-16.8.1.tgz#a80141e246eb894824fb4f2901c0c50ef31d4cdb"
+  integrity sha512-ioMCzVDWvCvKD8eeT+iukyWrBGrA3DiFYkXfBsVYIRdaREZuBjENG+KjrikavCLasozqRWTwFUagU/O4vPpRMA==
+
 react-lifecycles-compat@^3.0.4:
   version "3.0.4"
   resolved "https://registry.yarnpkg.com/react-lifecycles-compat/-/react-lifecycles-compat-3.0.4.tgz#4f1a273afdfc8f3488a8c516bfda78f872352362"