close input stream after each run

Author: kolea2

datastore-v1-proto-client/src/test/java/com/google/datastore/v1/client/ChecksumEnforcingInputStreamTest.java

@@ -42,6 +42,8 @@ public void test(int payloadSize) throws Exception {
       }
     } catch (IOException e) {
       fail("checksum verification failed!");
+    } finally {
+      testInstance.close();
     }
   }