Use official codespell action for spell check CI

The arduino/actions/libraries/spell-check action previously in use is deprecated.

In the event of a false positive, the problematic word should be added, in all lowercase, to the `ignore-words-list` field of `./.codespellrc`. Regardless of the case of the word in the false positive, it must be in all lowercase in the ignore list. The ignore list is comma-separated with no spaces.

Author: per1234

.codespellrc

@@ -0,0 +1,7 @@
+# See: https://github.com/codespell-project/codespell#using-a-config-file
+[codespell]
+# In the event of a false positive, add the problematic word, in all lowercase, to a comma-separated list here:
+ignore-words-list = ,
+check-filenames =
+check-hidden =
+skip = ./.git,./extras/TrustAnchors,./src/bearssl

.github/workflows/spell-check.yml

@@ -1,17 +1,22 @@
 name: Spell Check
 
-on: [push, pull_request]
+# See: https://docs.github.com/en/free-pro-team@latest/actions/reference/events-that-trigger-workflows
+on:
+  push:
+  pull_request:
+  schedule:
+    # Run every Tuesday at 8 AM UTC to catch new misspelling detections resulting from dictionary updates.
+    - cron: "0 8 * * TUE"
+  workflow_dispatch:
+  repository_dispatch:
 
 jobs:
   spellcheck:
     runs-on: ubuntu-latest
 
     steps:
-      - name: Checkout
+      - name: Checkout repository
         uses: actions/checkout@v2
 
       - name: Spell check
-        uses: arduino/actions/libraries/spell-check@master
-        with:
-          ignore-words-list: extras/codespell-ignore-words-list.txt
-          skip-paths: ./extras/TrustAnchors,./src/bearssl
+        uses: codespell-project/actions-codespell@master