Update protobuf requirement from <6,>=5.29.2 to >=5.29.2,<7 (#127)

Updates the requirements on
[protobuf](https://github.com/protocolbuffers/protobuf) to permit the
latest version.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/43e1626812c1b543e56a7bec59dc09eb18248bd2"><code>43e1626</code></a>
Updating version.json and repo version numbers to: 30.2</li>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/7a4c63bac3451b8adf8dd51e9c16ed74d4cbc662"><code>7a4c63b</code></a>
Fix lite classes in the protobuf-java Maven release to be JDK8
compatible. (#...</li>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/783166965aa8808ec1b74d4890088e3b0799ac08"><code>7831669</code></a>
Remove dllexport attribute on variable definition. (<a
href="https://redirect.github.com/protocolbuffers/protobuf/issues/20833">#20833</a>)</li>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/da9cadcb975654e3d158796b642ec27ba5f4509d"><code>da9cadc</code></a>
Restore JDK8 compatibility in Bazel for libraries with dependencies from
Mave...</li>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/09b5078524d60917d1fa8c635bcee52e608f2f04"><code>09b5078</code></a>
Add protobuf_maven artifacts to protobuf_maven_dev as well so they can
still ...</li>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/b7f06f1ed07a463a9279f7019653fe6c3e90282d"><code>b7f06f1</code></a>
Add volatile to featuresResolved (<a
href="https://redirect.github.com/protocolbuffers/protobuf/issues/20766">#20766</a>)</li>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/b69f653d6ebc90d88032b8cc82d626758a74ef77"><code>b69f653</code></a>
Restore generator headers in cmake install until the next breaking C++
releas...</li>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/f4b0a79783aa1c579bfe005908f723fdc6d68169"><code>f4b0a79</code></a>
Restore custom protobuf maven namespaces to avoid polluting main maven
namesp...</li>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/2dc9f35e83f4b55e58443421266b0f9a158d91dd"><code>2dc9f35</code></a>
Fix Java concurrency issue in feature resolution for old &lt;=3.25.x
gencode usi...</li>
<li><a
href="https://github.com/protocolbuffers/protobuf/commit/221b2a0081ebdba6cf3b7278bf65528316ba4480"><code>221b2a0</code></a>
Change how we decide which empty string implementation to use. (<a
href="https://redirect.github.com/protocolbuffers/protobuf/issues/20708">#20708</a>)</li>
<li>Additional commits viewable in <a
href="https://github.com/protocolbuffers/protobuf/compare/v5.29.2...v6.30.2">compare
view</a></li>
</ul>
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</details>

Author: matthias-wende-frequenz

pyproject.toml

@@ -46,7 +46,7 @@ dependencies = [
   "frequenz-client-base >= 0.9.0, < 0.10.0",
   "frequenz-client-common >= 0.1.0, < 0.4.0",
   "frequenz-api-electricity-trading >= 0.6.1, < 0.7.0",
-  "protobuf >= 5.29.2, < 6",
+  "protobuf >= 5.29.2, < 7",
 ]
 dynamic = ["version"]