Bump core from 73fdcfd to b6c00a8 (#2321)

Bumps [core](https://github.com/microsoft/typespec) from `73fdcfd` to
`b6c00a8`.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/microsoft/typespec/commit/b6c00a8d5bf0c8cba11b77a528b85a4356e6e0c7"><code>b6c00a8</code></a>
Revert &quot;[python] add bump for dev version for
http-client-python&quot; (<a
href="https://redirect.github.com/microsoft/typespec/issues/6296">#6296</a>)</li>
<li><a
href="https://github.com/microsoft/typespec/commit/6875a0029fe20d309ed0d1d046035bc3d1a8bad1"><code>6875a00</code></a>
[python] bump tsp 0.66.0 (<a
href="https://redirect.github.com/microsoft/typespec/issues/6293">#6293</a>)</li>
<li>See full diff in <a
href="https://github.com/microsoft/typespec/compare/73fdcfd1dcf8e8170812c44ee01fff023f19f34d...b6c00a8d5bf0c8cba11b77a528b85a4356e6e0c7">compare
view</a></li>
</ul>
</details>
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