FABJ-483: Update dependency in test chaincode

Update the dependency on com.github.johnrengelman.shadow in the
test chaincode to match a gradle upgrade in the chaincode
container.

Change-Id: I28aa6daccfa2aa61fa44206e3437489511120258
Signed-off-by: Mark S. Lewis <mark_lewis@uk.ibm.com>

src/test/fixture/sdkintegration/javacc/sample1/build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id 'com.github.johnrengelman.shadow' version '2.0.3'
+    id 'com.github.johnrengelman.shadow' version '5.1.0'
     id 'java'
 }