Drop slf4j-test from webauthn-server-attestation test dependencies

This prevents the unit test XML reports from containing large stdout
logs which are not used for anything but crash the default settings of
EnricoMi/publish-unit-test-result-action@v2 .

This was originally done in commit cdf9513 and
then undone for no apparent reason in efa4b00.
The tests added in efa4b00 do not use any of
the features of `slf4j-test`; it appears the dependency was re-added solely for
capturing log output.

Author: emlun

webauthn-server-attestation/build.gradle.kts

@@ -45,13 +45,7 @@ dependencies {
   testImplementation("org.scalatest:scalatest_2.13")
   testImplementation("org.scalatestplus:junit-4-13_2.13")
   testImplementation("org.scalatestplus:scalacheck-1-16_2.13")
-
-  testImplementation("org.slf4j:slf4j-api") {
-    version {
-      strictly("[1.7.25,1.8-a)") // Pre-1.8 version required by slf4j-test
-    }
-  }
-  testRuntimeOnly("uk.org.lidalia:slf4j-test")
+  testImplementation("org.slf4j:slf4j-api")
 }
 
 val integrationTest = task<Test>("integrationTest") {