Bump mypy from 1.3.0 to 1.4.0 (#458)

Bumps [mypy](https://github.com/python/mypy) from 1.3.0 to 1.4.0.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/python/mypy/commit/be5f84b853d15bbbdd3185349fa8e285f7e19bf3"><code>be5f84b</code></a>
Remove +dev from version.</li>
<li><a
href="https://github.com/python/mypy/commit/d61383eef28aeef5aa4549e9fd53fb4acc0a4855"><code>d61383e</code></a>
Always allow returning Any from lambda (<a
href="https://redirect.github.com/python/mypy/issues/15413">#15413</a>)</li>
<li><a
href="https://github.com/python/mypy/commit/fa05ab97eae4922e392f5adda1dc51e2ad4e7a0c"><code>fa05ab9</code></a>
Fix crash on follow_imports_for_stubs (<a
href="https://redirect.github.com/python/mypy/issues/15407">#15407</a>)</li>
<li><a
href="https://github.com/python/mypy/commit/cec31d67669c6c5ac907d40466892341a3f49933"><code>cec31d6</code></a>
Fix stubtest crash in explicit init subclass (<a
href="https://redirect.github.com/python/mypy/issues/15399">#15399</a>)</li>
<li><a
href="https://github.com/python/mypy/commit/7886503525819d36df2c440f8c4b03f9c66a38ae"><code>7886503</code></a>
Fix crash when indexing TypedDict with empty key (<a
href="https://redirect.github.com/python/mypy/issues/15392">#15392</a>)</li>
<li><a
href="https://github.com/python/mypy/commit/5e6e488e76c1970aa0a13bee264ee85cf73e97b4"><code>5e6e488</code></a>
Fix crash on NamedTuple as attribute (<a
href="https://redirect.github.com/python/mypy/issues/15404">#15404</a>)</li>
<li><a
href="https://github.com/python/mypy/commit/9caf0959b81db108fffed1423c926f83148ec293"><code>9caf095</code></a>
Correctly track loop depth for nested functions/classes (<a
href="https://redirect.github.com/python/mypy/issues/15403">#15403</a>)</li>
<li><a
href="https://github.com/python/mypy/commit/a7f52db0e69db0bd7d97e548c9b69667a143a451"><code>a7f52db</code></a>
Fix crash on joins with recursive tuples (<a
href="https://redirect.github.com/python/mypy/issues/15402">#15402</a>)</li>
<li><a
href="https://github.com/python/mypy/commit/3bf9fdc347ff1d27baead7660442d645a77cb2c6"><code>3bf9fdc</code></a>
Revert &quot;Add support for <code>attrs.fields</code> (<a
href="https://redirect.github.com/python/mypy/issues/15021">#15021</a>)&quot;</li>
<li><a
href="https://github.com/python/mypy/commit/2ab8849f6460fe586a1a1add3a006ce4edd3fb75"><code>2ab8849</code></a>
Update semantic analyzer for TypeVar defaults (PEP 696) (<a
href="https://redirect.github.com/python/mypy/issues/14873">#14873</a>)</li>
<li>Additional commits viewable in <a
href="https://github.com/python/mypy/compare/v1.3.0...v1.4.0">compare
view</a></li>
</ul>
</details>
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</details>

Author: llucax

pyproject.toml

@@ -72,7 +72,7 @@ pytest = [
   "frequenz-sdk[examples]",
 ]
 mypy = [
-  "mypy == 1.3.0",
+  "mypy == 1.4.0",
   "grpc-stubs == 1.24.12", # This dependency introduces breaking changes in patch releases
   # For checking the noxfile, docs/ script, and tests
   "frequenz-sdk[docs-gen,nox,pytest]",