remove version from 6 node graph

Author: josibake

test/data/6_node_ring.graphml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?><graphml xmlns="http://graphml.graphdrawing.org/xmlns">
   <key id="services"        attr.name="services"         attr.type="string"   for="graph" />
-  <key id="version"         attr.name="version"          attr.type="string"   for="node" />
   <key id="image"           attr.name="image"            attr.type="string"   for="node" />
   <key id="bitcoin_config"  attr.name="bitcoin_config"   attr.type="string"   for="node" />
   <key id="tc_netem"        attr.name="tc_netem"         attr.type="string"   for="node" />
@@ -17,27 +16,27 @@
   <key id="target_policy"   attr.name="target_policy"    attr.type="string"   for="edge" />
   <graph edgedefault="directed">
     <node id="0">
-        <data key="version">27.0</data>
+        <data key="image">bitcoindevproject/bitcoin:v27.0</data>
         <data key="bitcoin_config">-uacomment=w0 -debug=validation</data>
     </node>
     <node id="1">
-        <data key="version">27.0</data>
+        <data key="image">bitcoindevproject/bitcoin:v27.0</data>
         <data key="bitcoin_config">-uacomment=w1 -debug=validation</data>
     </node>
     <node id="2">
-        <data key="version">27.0</data>
+        <data key="image">bitcoindevproject/bitcoin:v27.0</data>
         <data key="bitcoin_config">-uacomment=w2 -debug=validation</data>
     </node>
     <node id="3">
-        <data key="version">27.0</data>
+        <data key="image">bitcoindevproject/bitcoin:v27.0</data>
         <data key="bitcoin_config">-uacomment=w3</data>
     </node>
     <node id="4">
-        <data key="version">27.0</data>
+        <data key="image">bitcoindevproject/bitcoin:v27.0</data>
         <data key="bitcoin_config">-uacomment=w4</data>
     </node>
     <node id="5">
-        <data key="version">27.0</data>
+        <data key="image">bitcoindevproject/bitcoin:v27.0</data>
         <!-- no bitcoin_config to test unused options -->
     </node>
     <!-- connect the nodes in a ring to start -->