fix: use MIT on all package.json files

packages/components/package.json

@@ -2,6 +2,7 @@
   "name": "pubsweet-components",
   "version": "6.2.0",
   "private": true,
+  "license": "MIT",
   "scripts": {
     "test": "jest --coverage"
   },

packages/components/xpub-edit/package.json

 {
   "name": "xpub-edit",
   "version": "0.1.3",
+  "license": "MIT",
   "files": [
     "dist",
     "src"

packages/components/xpub-manuscript/package.json

 {
   "name": "pubsweet-component-xpub-manuscript",
   "version": "0.0.16",
+  "license": "MIT",
   "files": [
     "src",
     "dist"

packages/components/xpub-styleguide/package.json

 {
   "name": "xpub-styleguide",
   "version": "0.0.14",
+  "license": "MIT",
   "files": [
     "src",
     "dist"

packages/jest-environment-db/package.json

@@ -9,7 +9,7 @@
   },
   "keywords": [],
   "author": "",
-  "license": "ISC",
+  "license": "MIT",
   "dependencies": {
     "jest-environment-node": "^22.1.4"
   }

packages/styleguide/package.json

 {
   "name": "@pubsweet/styleguide",
   "version": "1.3.2",
+  "license": "MIT",
   "files": [
     "src",
     "dist"

packages/ui/package.json

 {
   "name": "@pubsweet/ui",
   "version": "4.1.1",
+  "license": "MIT",
   "files": [
     "docs",
     "dist",