Apparently, this is intended behavior:
com.firebaseui:firebase-ui-firestore:3.1.0 depends on android.arch.lifecycle:extensions:1.0.0-beta1. Switching to version 3.2.2 fixes the issue by using the Lifecycle 1.1 libraries that Support Library 27.1.0 are built upon. - Issue Tracker
For me, removing the firebase-ui dependencies solved the issue since I wasn't even using the library in the first place.
You can specify the Gradle version in either the File > Project Structure > Project menu in Android Studio, or by editing the Gradle distribution reference in the gradle/wrapper/gradle-wrapper.properties file. The following example sets the Gradle version to 4.10.1 in the gradle-wrapper.properties file.
...
distributionUrl = https\://services.gradle.org/distributions/gradle-4.10.1-all.zip
...