test(jspg): rename items fixture to array and resolve unused HashMap warning

- Rename fixtures/items.json to fixtures/array.json to better reflect array testing constraints.
- Update reference paths in src/tests/fixtures.rs and across other fixture JSON files.
- Remove unused HashMap import in src/validator/rules/dict.rs to resolve the compiler warning.

fixtures/exclusiveMaximum.json

@@ -34,8 +34,8 @@
             {
               "code": "EXCLUSIVE_MAXIMUM_VIOLATED",
               "values": {
-                "value": "3",
-                "limit": "3"
+                "limit": "3",
+                "value": "3"
               },
               "details": {
                 "path": "",
@@ -56,8 +56,8 @@
             {
               "code": "EXCLUSIVE_MAXIMUM_VIOLATED",
               "values": {
-                "value": "3.5",
-                "limit": "3"
+                "limit": "3",
+                "value": "3.5"
               },
               "details": {
                 "path": "",