Bump assertj-core from 3.16.1 to 3.17.0

Bumps [assertj-core](https://github.com/joel-costigliola/assertj-core) from 3.16.1 to 3.17.0.
- [Release notes](https://github.com/joel-costigliola/assertj-core/releases)
- [Commits](assertj/assertj@assertj-core-3.16.1...assertj-core-3.17.0)

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

sense-hat/build.gradle

@@ -10,5 +10,5 @@ dependencies {
     compile 'com.squareup.okio:okio:2.8.0'
 
     testCompile 'junit:junit:4.13'
-    testCompile 'org.assertj:assertj-core:3.16.1'
+    testCompile 'org.assertj:assertj-core:3.17.0'
 }