feat: PowerShell 7.5 support

[vaind]

We need to use net9 for PowerShell 7.5, otherwise the module can't be loaded because sentry.dll with net8 doesn't match the runtime version used by PowerShell 7.5 (net9)

note: this also adds a missing changelog item for dropping support of older pwsh versions which happened in #71

[github-actions]

	Fails
🚫	Please consider adding a changelog entry for the next release.

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Instructions and example for changelog

Please add an entry to CHANGELOG.md to the "Unreleased" section. Make sure the entry includes this PR's number.

Example:

## Unreleased

- PowerShell 7.5 support ([#76](https://github.com/getsentry/sentry-powershell/pull/76))

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