Bump AkkaVersion from 1.4.18 to 1.4.21 (#92)
Bump AkkaVersion from 1.4.18 to 1.4.21 (#92)

Bumps `AkkaVersion` from 1.4.18 to 1.4.21.

Updates `Akka.DI.Core` from 1.4.18 to 1.4.21
- [Release notes](https://github.com/akkadotnet/akka.net/releases)
- [Changelog](https://github.com/akkadotnet/akka.net/blob/dev/RELEASE_NOTES.md)
- [Commits](https://github.com/akkadotnet/akka.net/compare/1.4.18...1.4.21)

Updates `Akka.DI.TestKit` from 1.4.18 to 1.4.21
- [Release notes](https://github.com/akkadotnet/akka.net/releases)
- [Changelog](https://github.com/akkadotnet/akka.net/blob/dev/RELEASE_NOTES.md)
- [Commits](https://github.com/akkadotnet/akka.net/compare/1.4.18...1.4.21)

Updates `Akka.TestKit.Xunit2` from 1.4.18 to 1.4.21
- [Release notes](https://github.com/akkadotnet/akka.net/releases)
- [Changelog](https://github.com/akkadotnet/akka.net/blob/dev/RELEASE_NOTES.md)
- [Commits](https://github.com/akkadotnet/akka.net/compare/1.4.18...1.4.21)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>

Co-authored-by: dependabot-preview[bot] <6a4c1c4838f800d1998274cd5234e1f65c55e90c@users.noreply.github.com>
akkadotnet/Akka.DI.AutoFac,akkadotnet/Akka.DI.AutoFac