3.3: adapt closures sample

samples have been structured to be implemented one by one,
and the closures sample is meant to be handled before implementing maps and lists.

Author: divarvel

biscuit/test/samples/current/samples.json

@@ -2800,15 +2800,15 @@
               }
             ],
             "policies": [
-              "allow if [true].any($p -> [true].all($p -> $p))"
+              "allow if {true}.any($p -> {true}.all($p -> $p))"
             ]
           },
           "result": {
             "Err": {
               "Execution": "ShadowedVariable"
             }
           },
-          "authorizer_code": "allow if [true].any($p -> [true].all($p -> $p));\n",
+          "authorizer_code": "allow if {true}.any($p -> {true}.all($p -> $p));\n",
           "revocation_ids": [
             "2cd348b6df5f08b900903fd8d3fbea0bb89b665c331a2aa2131e0b8ecb38b3550275d4ccd8db35da6c4433eed1d456cfb761e3fcc7845894d891e986ca044b02"
           ]