Update slf4j-simple to 2.x in test scope

This eliminates the SLF4J warnings relating to:
> Class path contains SLF4J bindings targeting
> slf4j-api versions 1.7.x or earlier

See https://www.slf4j.org/codes.html#ignoredBindings for details.

(The hardcoded version will only be necessary until pom-scijava
upgrades from 1.7.36 to 2.x.)

Author: ctrueden

build.gradle.kts

@@ -115,12 +115,11 @@ dependencies {
     implementation("org.janelia.saalfeldlab:n5")
     implementation("org.janelia.saalfeldlab:n5-hdf5")
     implementation("sc.fiji:spim_data")
-    implementation("org.slf4j:slf4j-simple")
 
     implementation(platform(kotlin("bom")))
     implementation(kotlin("stdlib-jdk8"))
     testImplementation(kotlin("test-junit"))
-    testImplementation("org.slf4j:slf4j-simple")
+    testImplementation("org.slf4j:slf4j-simple:2.0.16")
 
     implementation("sc.fiji:bigdataviewer-core")
     implementation("sc.fiji:bigdataviewer-vistools")