Update tinymce-a11y-checker version usage

fixes MAT-517

flag=none

Test plan (copied from MAT-464):
- Navigate to an RCE instance
- Upload an image (jpg, png mainly) and assign an alt attribute
as a filename with spaces (i.e this image.jpg)
- After upload and preview, click the accesibility checker.
> Verify it must warn of a filename not allowed as an alt attribute

Change-Id: Id7fb911db5d1090c192be90cf9c5b2537942d5d9
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/279220
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Weston Dransfield <wdransfield@instructure.com>
QA-Review: Weston Dransfield <wdransfield@instructure.com>
Product-Review: Juan Chavez <juan.chavez@instructure.com>

package.json

@@ -170,7 +170,7 @@
     "tablesorter": "^2.28.5",
     "timezone": "https://registry.npmjs.org/@brentburgoyne/timezone/-/timezone-1.0.24.tgz",
     "tinycolor2": "1.4.1",
-    "tinymce-a11y-checker": "^3.2.0",
+    "tinymce-a11y-checker": "^3.3.1",
     "use-debounce": "^3",
     "use-media-set": "^1.1",
     "uuid": "^3.2.1",

packages/canvas-rce/package.json

@@ -132,7 +132,7 @@
     "redux-thunk": "^2",
     "scroll-into-view": "https://github.com/bkirkby/scroll-into-view.git#588b0ced98eeecf84e6fb2074aa076e80b7cffab",
     "tinymce": "^5",
-    "tinymce-a11y-checker": "^3.0.0"
+    "tinymce-a11y-checker": "^3.3.1"
   },
   "devDependencies": {
     "@babel/cli": "^7",

yarn.lock

@@ -24390,10 +24390,10 @@ tinycolor2@^1.4.1:
   resolved "https://registry.yarnpkg.com/tinycolor2/-/tinycolor2-1.4.2.tgz#3f6a4d1071ad07676d7fa472e1fac40a719d8803"
   integrity sha512-vJhccZPs965sV/L2sU4oRQVAos0pQXwsvTLkWYdqJ+a8Q5kPFzJTuOFwy7UniPli44NKQGAglksjvOcpo95aZA==
 
-tinymce-a11y-checker@^3.0.0, tinymce-a11y-checker@^3.2.0:
-  version "3.2.0"
-  resolved "https://registry.yarnpkg.com/tinymce-a11y-checker/-/tinymce-a11y-checker-3.2.0.tgz#bef9ba0d6998ba1bf88ca7397e9b224b55e34d57"
-  integrity sha512-LFdYB8ZMA2eLWQ4m+GiMqps+3e7iCuJo7Uqy0Q2fptslgUNV86hgtbWA0f5lA6Izs751tA3JoqPCaqSTgjWFmw==
+tinymce-a11y-checker@^3.3.1:
+  version "3.3.1"
+  resolved "https://registry.yarnpkg.com/tinymce-a11y-checker/-/tinymce-a11y-checker-3.3.1.tgz#e54253ca82771a0d4a99f67d5ee5458fd51179a0"
+  integrity sha512-IarvyQHscfbBEDpp6vMU8r6ksouwd7ozkdlEwksCS30G0wi+ZtXyOvEBUyRd7uO2DfMnFLs7QWDdsUiqruLf4Q==
   dependencies:
     "@instructure/canvas-theme" "^7.6.0"
     "@instructure/ui-a11y-content" "^7.6.0"