Roll Packages from a757073ac4ea to a2f4ce0a5057 (3 revisions) (#145399)

https://github.com/flutter/packages/compare/a757073ac4ea...a2f4ce0a5057

2024-03-18 49699333+dependabot[bot]@users.noreply.github.com [sign_in]: Bump com.google.android.gms:play-services-auth from 20.7.0 to 21.0.0 in /packages/google_sign_in/google_sign_in_android/android (flutter/packages#6159)
2024-03-18 engine-flutter-autoroll@skia.org Roll Flutter from 7c860ddf to f217fc17 (9 revisions) (flutter/packages#6350)
2024-03-18 16229121+leiatfly@users.noreply.github.com [flutter_markdown] Adds onSelectionChanged in Markdown (flutter/packages#6169)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-packages-flutter-autoroll
Please CC flutter-ecosystem@google.com,rmistry@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

bin/internal/flutter_packages.version

-a757073ac4eaf05b7516d3d0488e5c98b221043f
+a2f4ce0a50570a623e54788901314b5f8352c0cc