remove cflinuxfs3 from tests (cf int env now only supports cflinuxfs4)

Author: patrickcrocker

README.md

@@ -1267,7 +1267,7 @@ Update a buildpack
   params:
     command: update-buildpack
     buildpack: java_buildpack_offline
-    assign_stack: cflinuxfs3
+    assign_stack: cflinuxfs4
 ```
 
 ### `delete-buildpack`
@@ -1284,7 +1284,7 @@ Delete a buildpack
   params:
     command: delete-buildpack
     buildpack: java_buildpack_offline
-    stack: cflinuxfs3
+    stack: cflinuxfs4
 ```
 
 ### `run-task`

spec/buildpacks/create-buildpack_spec.sh

@@ -52,15 +52,15 @@ Describe 'buildpacks'
         #|params:
         #|  command: update-buildpack
         #|  buildpack: $buildpack
-        #|  assign_stack: cflinuxfs3
+        #|  assign_stack: cflinuxfs4
       )
       put "$config"
     }
     When call assign_stack
     The status should be success
     The output should json '.version | keys == ["timestamp"]'
     The error should include "Assigning stack"
-    Assert [ "cflinuxfs3" == "$(cf::get_buildpack_stack "$buildpack")" ]
+    Assert [ "cflinuxfs4" == "$(cf::get_buildpack_stack "$buildpack")" ]
   End
 
   It 'can update a buildpack path'
@@ -189,7 +189,7 @@ Describe 'buildpacks'
         #|params:
         #|  command: delete-buildpack
         #|  buildpack: $buildpack
-        #|  stack: cflinuxfs3
+        #|  stack: cflinuxfs4
       )
       put "$config"
     }