Update linux-install-manually.md

[PaleSkinnySwede]

Changed apt-get to apt since that's a newer version.

[learn-build-service-prod]

Learn Build status updates of commit 7cfc1e3:

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[learn-build-service-prod]

Learn Build status updates of commit 073644c:

✅ Validation status: passed

File	Status	Preview URL	Details
defender-endpoint/linux-install-manually.md	✅Succeeded

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[denisebmsft]

Thank you for the pull request, @PaleSkinnySwede! We'll get this merged soon.

[learn-build-service-prod]

Learn Build status updates of commit ebf869c:

✅ Validation status: passed

File	Status	Preview URL	Details
defender-endpoint/linux-install-manually.md	✅Succeeded

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel