Update watchfiles requirement from <0.21.0,>=0.15.0 to >=0.15.0,<0.22.0 (#211)

Updates the requirements on
[watchfiles](https://github.com/samuelcolvin/watchfiles) to permit the
latest version.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/samuelcolvin/watchfiles/releases">watchfiles's
releases</a>.</em></p>
<blockquote>
<h2>v0.21.0 2023-10-13</h2>
<h2>What's Changed</h2>
<ul>
<li>Add Python 3.12 support, drop Python 3.7 support by <a
href="https://github.com/gi0baro"><code>@​gi0baro</code></a> in <a
href="https://redirect.github.com/samuelcolvin/watchfiles/pull/248">samuelcolvin/watchfiles#248</a></li>
</ul>
<h2>New Contributors</h2>
<ul>
<li><a href="https://github.com/gi0baro"><code>@​gi0baro</code></a> made
their first contribution in <a
href="https://redirect.github.com/samuelcolvin/watchfiles/pull/248">samuelcolvin/watchfiles#248</a></li>
</ul>
<p><strong>Full Changelog</strong>: <a
href="https://github.com/samuelcolvin/watchfiles/compare/v0.20.0...v0.21.0">https://github.com/samuelcolvin/watchfiles/compare/v0.20.0...v0.21.0</a></p>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/6ea19cac0447b3594cca29793fe0d308c3585a6a"><code>6ea19ca</code></a>
Add Python 3.12 support, drop Python 3.7 support (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/248">#248</a>)</li>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/eb0df3a68cb6a6d3859422c357be47de9f5a50c2"><code>eb0df3a</code></a>
Catch <code>SIGTERM</code> and kill running process before exitting (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/244">#244</a>)</li>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/ea31274f4101229744e5fd90df5b74b69e44b53b"><code>ea31274</code></a>
Add ignore_permission_denied option (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/224">#224</a>)</li>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/ea789d34e0cbb5b4dc9e57f5379723b611af08e1"><code>ea789d3</code></a>
add grace period during which file changes are ignored (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/243">#243</a>)</li>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/79dd64723e577d85263f9be078e2ac7a69dc61e3"><code>79dd647</code></a>
Improve debug (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/242">#242</a>)</li>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/c2c750cb25a5595d28fd9b5736d483f881adeeda"><code>c2c750c</code></a>
Fix: Memory leak of PyO3 (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/240">#240</a>)</li>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/c08de3936f4cc393311e03eb6b4f30c5714a4c57"><code>c08de39</code></a>
Allow maturin 1.x (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/233">#233</a>)</li>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/8fc179652eeaa50f38bb52126c65e69a5c61152f"><code>8fc1796</code></a>
Bump pygments from 2.13.0 to 2.15.0 in /requirements (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/237">#237</a>)</li>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/d6867d7cafe31e9c144bb5a76b555d857988dcab"><code>d6867d7</code></a>
Bump pymdown-extensions from 9.5 to 10.0 in /requirements (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/229">#229</a>)</li>
<li><a
href="https://github.com/samuelcolvin/watchfiles/commit/da0c1f004069399ca9e5dde62e4eaeb5d4a603ea"><code>da0c1f0</code></a>
Update pyo3 to 0.18.2 (<a
href="https://redirect.github.com/samuelcolvin/watchfiles/issues/222">#222</a>)</li>
<li>Additional commits viewable in <a
href="https://github.com/samuelcolvin/watchfiles/compare/v0.15.0...v0.21.0">compare
view</a></li>
</ul>
</details>
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</details>

Author: Marenz

pyproject.toml

@@ -27,7 +27,7 @@ classifiers = [
 requires-python = ">= 3.11, < 4"
 dependencies = [
   "typing-extensions >= 4.5.0, < 5",
-  "watchfiles >= 0.15.0, < 0.21.0",
+  "watchfiles >= 0.15.0, < 0.22.0",
 ]
 dynamic = ["version"]