chore: Match the protoc version w/ the protobuf in the gradle build

Not specifying a protoc binary like this means it uses what's installed
on the system. This works fine if you're building via the docker setup,
but isn't very convenient if you're working from e.g. inside Android
Studio.

Author: robinlinden

docker/jvm.Dockerfile

@@ -40,7 +40,6 @@ COPY gradlew gradle.properties settings.gradle.kts /work/jvm-toxcore-c/
 COPY gradle /work/jvm-toxcore-c/gradle/
 COPY lib/ /work/jvm-toxcore-c/lib/
 ENV LD_LIBRARY_PATH=/work/jvm-toxcore-c/_install/host/lib
-ENV PATH=/work/jvm-toxcore-c/_install/host/bin:$PATH
 RUN ./gradlew build
 
 RUN javac -h . -cp /work/jvm-toxcore-c/lib/build/classes/kotlin/main:/work/jvm-toxcore-c/lib/build/classes/java/main \

lib/build.gradle.kts

@@ -11,11 +11,19 @@ repositories {
     mavenCentral()
 }
 
+val protobufVersion = "3.24.4"
+
 dependencies {
-    implementation("com.google.protobuf:protobuf-java:3.24.4")
+    implementation("com.google.protobuf:protobuf-java:$protobufVersion")
     testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.8.0")
 }
 
+protobuf {
+    protoc {
+        artifact = "com.google.protobuf:protoc:$protobufVersion"
+    }
+}
+
 testing {
     suites {
         // Configure the built-in test suite