Merged PR 32133: Update changelog for release v7.4.5

Update changelog for release v7.4.5

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#### AI description  (iteration 1)
#### PR Classification
Documentation update for the release of version 7.4.5.

#### PR Summary
This pull request updates the changelog to document the changes and improvements made in version 7.4.5.
- `CHANGELOG/7.4.md`: Added entries for general cmdlet updates, test improvements, build and packaging enhancements, and documentation fixes.

CHANGELOG/7.4.md

@@ -1,5 +1,45 @@
 # 7.4 Changelog
 
+## [7.4.5] - 2024-08-20
+
+### General Cmdlet Updates and Fixes
+
+- Fix WebCmdlets when `-Body` is specified but `ContentType` is not (#24145)
+
+### Tests
+
+- Rewrite the mac syslog tests to make them less flaky (#24152)
+
+### Build and Packaging Improvements
+
+<details>
+
+<summary>
+
+<p>Bump .NET SDK to 8.0.400</p>
+
+</summary>
+
+<ul>
+<li>Add feature flags for removing network isolation (Internal 32126)</li>
+<li>Update <code>ThirdPartyNotices.txt</code> for v7.4.5 (#24160)</li>
+<li>Update <code>cgmanifest.json</code> for v7.4.5 (#24159)</li>
+<li>Update .NET SDK to 8.0.400 (#24151)</li>
+<li>Cleanup unused csproj (#24146)</li>
+<li>Remember installation options and used them to initialize options for the next installation (#24143)</li>
+<li>Fix failures in GitHub action <code>markdown-link-check</code> (#24142)</li>
+<li>Use correct signing certificates for RPM and DEBs (#21522)</li>
+</ul>
+
+</details>
+
+### Documentation and Help Content
+
+- Update docs sample nuget.config (#24147)
+- Fix up broken links in Markdown files (#24144)
+
+[7.4.5]: https://github.com/PowerShell/PowerShell/compare/v7.4.4...v7.4.5
+
 ## [7.4.4] - 2024-07-18
 
 ### Engine Updates and Fixes