Bump org.scalatestplus:junit dependency version

(git cherry-pick a62d4c8)

Fixes this build failure that suddenly occurred with no code changes:

```
$ ./gradlew :webauthn-server-core:compileTestScala
Execution failed for task ':webauthn-server-core:compileTestScala'.
>
bad constant pool index: 0 at pos: 89856
while compiling: ./webauthn-server-core/src/test/scala/com/yubico/scalacheck/gen/JacksonGenerators.scala
during phase: globalPhase=typer, enteringPhase=namer
library version: version 2.13.8
compiler version: version 2.13.8
reconstructed args: [9876 characters redacted for brevity]

last tree to typer: Ident(com)
tree position: line 35 of ./webauthn-server-core/src/test/scala/com/yubico/scalacheck/gen/JacksonGenerators.scala
tree tpe: com.type
symbol: final package com
symbol definition: final package com (a ModuleSymbol)
symbol package: <none>
symbol owners: package com
call site: package gen in package scalacheck in package scalacheck

== Source file context for tree position ==

32 import com.fasterxml.jackson.databind.node.NumericNode
33 import com.fasterxml.jackson.databind.node.ObjectNode
34 import com.fasterxml.jackson.databind.node.TextNode
35 import com.upokecenter.cbor.CBORObject
36 import com.yubico.internal.util.JacksonCodecs
37 import org.scalacheck.Arbitrary
38 import org.scalacheck.Arbitrary.arbitrary
```

test-platform/build.gradle.kts

@@ -12,7 +12,7 @@ dependencies {
     api("org.mockito:mockito-core:4.7.0")
     api("org.scalacheck:scalacheck_2.13:1.16.0")
     api("org.scalatest:scalatest_2.13:3.2.13")
-    api("org.scalatestplus:junit-4-13_2.13:3.2.13.0")
+    api("org.scalatestplus:junit-4-13_2.13:3.2.17.0")
     api("org.scalatestplus:scalacheck-1-16_2.13:3.2.13.0")
     api("org.slf4j:slf4j-nop:2.0.3")
     api("uk.org.lidalia:slf4j-test:1.2.0")