Bump tinymce-a11y-checker to 1.3.0

closes CORE-826

Test Plan:
  - Load up an RCE instance in Canvas
  - Use the a11y checker to ensure that the following
    new features work:
      - Elements with only links don't trigger the a11y checker
        (commit: 8f88c941776583ec65dc97862fc0b30db175760e)
      - Captions with only whitespace on tables trigger it
        (commit: f22604c438e31508ca2e8f72317bbe1e07417e60)
      - Modifying a header that is in the wrong order becomes a <p>
        (commit: 5c78821102054fd060a1cf2ced76bbfd45ccb561)
      - The show learn link shouldn't show on headers too long errors
        (commit: 3df571c00fbffe2c2c49b00ab89227dc0c6fb2f5)

Change-Id: I39894cc8f8b9c3d9cbf7695be93335d84da11cfa
Reviewed-on: https://gerrit.instructure.com/137397
Tested-by: Jenkins
Reviewed-by: Ryan Shaw <ryan@instructure.com>
QA-Review: Tucker McKnight <tmcknight@instructure.com>
Product-Review: Clay Diffrient <cdiffrient@instructure.com>

package.json

@@ -62,7 +62,7 @@
     "timezone": "1.0.6",
     "tinycolor2": "1.4.1",
     "tinymce": "4.5.7",
-    "tinymce-a11y-checker": "1.2.3",
+    "tinymce-a11y-checker": "1.3.0",
     "tinymce-light-skin": "1.3.1"
   },
   "devDependencies": {

yarn.lock

@@ -10595,9 +10595,9 @@ tinycolor2@1.4.1, tinycolor2@^1.4.1:
   version "1.4.1"
   resolved "https://registry.yarnpkg.com/tinycolor2/-/tinycolor2-1.4.1.tgz#f4fad333447bc0b07d4dc8e9209d8f39a8ac77e8"
 
-tinymce-a11y-checker@1.2.3:
-  version "1.2.3"
-  resolved "https://registry.yarnpkg.com/tinymce-a11y-checker/-/tinymce-a11y-checker-1.2.3.tgz#540bf165666fc6191dcffa36117e2536e45968a1"
+tinymce-a11y-checker@1.3.0:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/tinymce-a11y-checker/-/tinymce-a11y-checker-1.3.0.tgz#2edfd53a83b666c5e9f1c961eb0821770b02d4cf"
   dependencies:
     format-message "^5.2.0"
     format-message-generate-id "^5.2.1"