build.gradle: Remove XZ for Java dependency

This was originally added in cd74930 in order
to support LZMA in Apache Commons Compress (included by Ghidra). Recent releases
of Ghidra already include XZ for Java, so there's no need to include it in
ghidra-firmware-utils. See #25 for more info.

build.gradle

@@ -77,23 +77,7 @@ model {
 	}
 }
 
-repositories {
-	mavenCentral()
-}
-
-configurations {
-	toCopy
-}
-
-dependencies {
-	toCopy group: "org.tukaani", name: "xz", version: "1.8"
-}
-
 task copyLibraries(type: Copy, dependsOn: "efidecompressSharedLibrary") {
-	copy {
-		from configurations.toCopy into "lib"
-	}
-
 	if (Os.isFamily(Os.FAMILY_MAC)) {
 		from "$buildDir/libs/efidecompress/shared/libefidecompress.dylib" into "os/mac_x86_64"
 	} else if (Os.isFamily(Os.FAMILY_UNIX)) {