Add junit-platform-launcher to test runtime

This is fix the following warning about using deprecated Gradle
features:

  The automatic loading of test framework implementation dependencies
  has been deprecated. This is scheduled to be removed in Gradle 9.0.
  Declare the desired test framework directly on the test suite or
  explicitly declare the test framework implementation dependencies on
  the test's runtime classpath. Consult the upgrading guide for
  further information:
  https://docs.gradle.org/8.7/userguide/upgrading_version_8.html#test_framework_implementation_dependencies

Author: kahgoh

exercises/concept/calculator-conundrum/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {

exercises/concept/football-match-reports/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {

exercises/concept/gotta-snatch-em-all/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {

exercises/concept/lasagna/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {

exercises/concept/secrets/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {

exercises/concept/tim-from-marketing/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {

exercises/concept/wizards-and-warriors-2/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {

exercises/concept/wizards-and-warriors/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {

exercises/practice/acronym/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {

exercises/practice/affine-cipher/build.gradle

@@ -10,6 +10,8 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.10.0")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.25.1"
+
+    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {