Bump slf4j-api from 2.0.0-alpha0 to 2.0.0-alpha1 (#5403)

* Bump slf4j-api from 2.0.0-alpha0 to 2.0.0-alpha1

Bumps [slf4j-api](https://github.com/qos-ch/slf4j) from 2.0.0-alpha0 to 2.0.0-alpha1.
- [Release notes](https://github.com/qos-ch/slf4j/releases)
- [Commits](https://github.com/qos-ch/slf4j/commits/v_2.0.0-alpha1)

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

* Pin log4j.plugins

build.gradle

@@ -164,9 +164,10 @@ dependencies {
     compile 'org.jsoup:jsoup:1.12.1'
     compile 'com.mashape.unirest:unirest-java:1.4.9'
 
-    compile 'org.slf4j:slf4j-api:2.0.0-alpha0'
+    compile 'org.slf4j:slf4j-api:2.0.0-alpha1'
     compile group: 'org.apache.logging.log4j', name: 'log4j-jcl', version: '3.0.0-20190915.182410-364'
     compile group: 'org.apache.logging.log4j', name: 'log4j-slf4j18-impl', version: '3.0.0-20190915.182922-250'
+    compile group: 'org.apache.logging.log4j', name: 'log4j-plugins', version: '3.0.0-20190915.182837-57'
     implementation group: 'org.apache.logging.log4j', name: 'log4j-api', version: '3.0.0-20190915.182113-372'
     compile group: 'org.apache.logging.log4j', name: 'log4j-core', version: '3.0.0-20190915.182215-368'
     annotationProcessor group: 'org.apache.logging.log4j', name: 'log4j-core', version: '3.0.0-20190915.182215-368'