make junit5 aggregator a java-library

in order to publish them in correct scope automatically. To get the
`checkUploadedArtifacts` not to fail, I have to change the order of
namespaces of the expected pom.

Note:
* I also replaced tabs with spaces in `junit5/aggregator/build.gradle`.
  But only one additinal line, so no separate commit.

Signed-off-by: Andreas Schmid <service@aaschmid.de>

archunit-junit/junit5/aggregator/build.gradle

@@ -1,13 +1,15 @@
+apply plugin: 'java-library'
+
 ext.moduleName = 'com.tngtech.archunit.junit5'
 
 sourceCompatibility = JavaVersion.VERSION_1_8
 targetCompatibility = JavaVersion.VERSION_1_8
 
 dependencies {
-	compile(project(":archunit-junit5-api"))
-	runtime(project(":archunit-junit5-engine"))
+    api(project(":archunit-junit5-api"))
+    implementation(project(":archunit-junit5-engine"))
 }
 
 shadowJar {
-	exclude '**'
+    exclude '**'
 }

build-steps/release/expected/archunit-junit5.pom

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+         xmlns="http://maven.apache.org/POM/4.0.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.tngtech.archunit</groupId>