chore: Bump github-pages from 214 to 215 in /docs (#272)

Bumps [github-pages](https://github.com/github/pages-gem) from 214 to 215.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/github/pages-gem/releases">github-pages's releases</a>.</em></p>
<blockquote>
<h2>v215</h2>
<p>Bump github-pages-health-check to v1.17.2 <a href="https://github-redirect.dependabot.com/github/pages-gem/issues/771">#771</a></p>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/github/pages-gem/commit/c4294e6e8c7039d285cd1232db17c004e930e108"><code>c4294e6</code></a> Bump 💎 to v215</li>
<li><a href="https://github.com/github/pages-gem/commit/36bb446a39ab79de6932ea39c312224ec1dc88c1"><code>36bb446</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/github/pages-gem/issues/771">#771</a> from github/hubot/github-pages-health-check-v1-17-2</li>
<li><a href="https://github.com/github/pages-gem/commit/c2b4d75f7f5da34883bb7020574d53ebf9eec4b4"><code>c2b4d75</code></a> Update github-pages-health-check to 💎 v1.17.2</li>
<li><a href="https://github.com/github/pages-gem/commit/75fd58be0f294a6bf55a1990643838d5984a1f62"><code>75fd58b</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/github/pages-gem/issues/770">#770</a> from github/hubot/github-pages-health-check-v1-17-1</li>
<li><a href="https://github.com/github/pages-gem/commit/216d12d4665f2d20e3e54dbb8bde9587934b76ec"><code>216d12d</code></a> Update github-pages-health-check to 💎 v1.17.1</li>
<li>See full diff in <a href="https://github.com/github/pages-gem/compare/v214...v215">compare view</a></li>
</ul>
</details>
<br />


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</details>

docs/Gemfile.lock

@@ -1,7 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (6.0.3.6)
+    activesupport (6.0.3.7)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
@@ -22,20 +22,28 @@ GEM
     em-websocket (0.5.2)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
-    ethon (0.12.0)
-      ffi (>= 1.3.0)
+    ethon (0.14.0)
+      ffi (>= 1.15.0)
     eventmachine (1.2.7)
-    execjs (2.7.0)
-    faraday (1.3.0)
+    execjs (2.8.1)
+    faraday (1.4.2)
+      faraday-em_http (~> 1.0)
+      faraday-em_synchrony (~> 1.0)
+      faraday-excon (~> 1.1)
       faraday-net_http (~> 1.0)
+      faraday-net_http_persistent (~> 1.1)
       multipart-post (>= 1.2, < 3)
-      ruby2_keywords
+      ruby2_keywords (>= 0.0.4)
+    faraday-em_http (1.0.0)
+    faraday-em_synchrony (1.0.0)
+    faraday-excon (1.1.0)
     faraday-net_http (1.0.1)
-    ffi (1.15.0)
+    faraday-net_http_persistent (1.1.0)
+    ffi (1.15.1)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
-    github-pages (214)
-      github-pages-health-check (= 1.17.0)
+    github-pages (215)
+      github-pages-health-check (= 1.17.2)
       jekyll (= 3.9.0)
       jekyll-avatar (= 0.7.0)
       jekyll-coffeescript (= 1.1.1)
@@ -78,7 +86,7 @@ GEM
       nokogiri (>= 1.10.4, < 2.0)
       rouge (= 3.26.0)
       terminal-table (~> 1.4)
-    github-pages-health-check (1.17.0)
+    github-pages-health-check (1.17.2)
       addressable (~> 2.3)
       dnsruby (~> 1.60)
       octokit (~> 4.0)
@@ -212,17 +220,17 @@ GEM
       jekyll-seo-tag (~> 2.1)
     minitest (5.14.4)
     multipart-post (2.1.1)
-    nokogiri (1.11.4)
+    nokogiri (1.11.5)
       mini_portile2 (~> 2.5.0)
       racc (~> 1.4)
-    octokit (4.20.0)
+    octokit (4.21.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (4.0.6)
     racc (1.5.2)
-    rb-fsevent (0.10.4)
+    rb-fsevent (0.11.0)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rexml (3.2.5)