build: fix Gradle warnings (#480)

Signed-off-by: Niels Pardon <[email protected]>

Author: nielspardon

core/build.gradle.kts

@@ -171,6 +171,7 @@ abstract class SubstraitSpecVersionValueSource :
 }
 
 tasks.register("writeManifest") {
+  val version = project.version
   doLast {
     val substraitSpecVersionProvider =
       providers.of(SubstraitSpecVersionValueSource::class) {
@@ -187,7 +188,7 @@ tasks.register("writeManifest") {
     manifestFile.printWriter(StandardCharsets.UTF_8).use {
       it.println("Manifest-Version: 1.0")
       it.println("Implementation-Title: substrait-java")
-      it.println("Implementation-Version: " + project.version)
+      it.println("Implementation-Version: " + version)
       it.println("Specification-Title: substrait")
       it.println("Specification-Version: " + substraitSpecVersionProvider.get())
     }

isthmus-cli/build.gradle.kts

@@ -140,6 +140,7 @@ graal {
 }
 
 tasks.register("writeIsthmusVersion") {
+  val version = project.version
   doLast {
     val isthmusVersionClass =
       layout.buildDirectory
@@ -155,7 +156,7 @@ tasks.register("writeIsthmusVersion") {
       it.println("public class IsthmusCliVersion implements IVersionProvider {")
       it.println("  public String[] getVersion() throws Exception {")
       it.println("    return new String[] {")
-      it.println("        \"\${COMMAND-NAME} version " + project.version + "\",")
+      it.println("        \"\${COMMAND-NAME} version " + version + "\",")
       it.println("        \"Substrait version \" + SubstraitVersion.VERSION,")
       it.println("};")
       it.println("  }")