Remove jCenter from build.gradle

[EKT2000]

Hello,

`

Could not resolve all artifacts for configuration ':stream-io_flat-list-mvcp:releaseRuntimeClasspath'.
Could not resolve com.facebook.react:react-native:+.
Required by:
project :stream-io_flat-list-mvcp
> Failed to list versions for com.facebook.react:react-native.
> Unable to load Maven meta-data from https://jcenter.bintray.com/com/facebook/react/react-native/maven-metadata.xml.
> Could not HEAD 'https://jcenter.bintray.com/com/facebook/react/react-native/maven-metadata.xml'.
> Read timed out
``

jcenter.binary is not accessible anymore. Is there any possibility to change jCenter() to mavenCentral()?

[vanGalilea]

@EKT2000, thanks for reaching out, would you mind raising a PR for that? This will be much appreciated 😁

[EKT2000]

Yes, I hope this is correct (#45). I am a newbie and this is my first PR.