Do not enforce minimum value of page_number at model level

- This is to avoid spurious constraints being added to the OpenAPI
  schema
- Instead, validate the value on creation of overall QueryParameter
  model.

openapi/index_openapi.json

@@ -199,7 +199,6 @@
             "required": false,
             "schema": {
               "title": "Page Number",
-              "minimum": 1.0,
               "type": "integer",
               "description": "RECOMMENDED for use with _page-based_ pagination: using `page_number` and `page_limit` is RECOMMENDED.\nIt is RECOMMENDED that the first page has number 1, i.e., that `page_number` is 1-based.\nExample: Fetch page 2 of up to 50 structures per page: `/structures?page_number=2&page_limit=50`."
             },
@@ -510,15 +509,15 @@
             "title": "Id",
             "type": "string",
             "description": "An entry's ID as defined in section Definition of Terms.\n\n- **Type**: string.\n\n- **Requirements/Conventions**:\n    - **Support**: MUST be supported by all implementations, MUST NOT be `null`.\n    - **Query**: MUST be a queryable property with support for all mandatory filter features.\n    - **Response**: REQUIRED in the response.\n\n- **Examples**:\n    - `\"db/1234567\"`\n    - `\"cod/2000000\"`\n    - `\"cod/2000000@1234567\"`\n    - `\"nomad/L1234567890\"`\n    - `\"42\"`",
-            "x-optimade-support": "must",
-            "x-optimade-queryable": "must"
+            "x-optimade-queryable": "must",
+            "x-optimade-support": "must"
           },
           "type": {
             "title": "Type",
             "type": "string",
             "description": "The name of the type of an entry.\n\n- **Type**: string.\n\n- **Requirements/Conventions**:\n    - **Support**: MUST be supported by all implementations, MUST NOT be `null`.\n    - **Query**: MUST be a queryable property with support for all mandatory filter features.\n    - **Response**: REQUIRED in the response.\n    - MUST be an existing entry type.\n    - The entry of type `<type>` and ID `<id>` MUST be returned in response to a request for `/<type>/<id>` under the versioned base URL.\n\n- **Example**: `\"structures\"`",
-            "x-optimade-support": "must",
-            "x-optimade-queryable": "must"
+            "x-optimade-queryable": "must",
+            "x-optimade-support": "must"
           },
           "links": {
             "title": "Links",
@@ -570,8 +569,8 @@
             "title": "Immutable Id",
             "type": "string",
             "description": "The entry's immutable ID (e.g., an UUID). This is important for databases having preferred IDs that point to \"the latest version\" of a record, but still offer access to older variants. This ID maps to the version-specific record, in case it changes in the future.\n\n- **Type**: string.\n\n- **Requirements/Conventions**:\n    - **Support**: OPTIONAL support in implementations, i.e., MAY be `null`.\n    - **Query**: MUST be a queryable property with support for all mandatory filter features.\n\n- **Examples**:\n    - `\"8bd3e750-b477-41a0-9b11-3a799f21b44f\"`\n    - `\"fjeiwoj,54;@=%<>#32\"` (Strings that are not URL-safe are allowed.)",
-            "x-optimade-support": "optional",
-            "x-optimade-queryable": "must"
+            "x-optimade-queryable": "must",
+            "x-optimade-support": "optional"
           },
           "last_modified": {
             "title": "Last Modified",
@@ -1119,8 +1118,8 @@
             "title": "Id",
             "type": "string",
             "description": "An entry's ID as defined in section Definition of Terms.\n\n- **Type**: string.\n\n- **Requirements/Conventions**:\n    - **Support**: MUST be supported by all implementations, MUST NOT be `null`.\n    - **Query**: MUST be a queryable property with support for all mandatory filter features.\n    - **Response**: REQUIRED in the response.\n\n- **Examples**:\n    - `\"db/1234567\"`\n    - `\"cod/2000000\"`\n    - `\"cod/2000000@1234567\"`\n    - `\"nomad/L1234567890\"`\n    - `\"42\"`",
-            "x-optimade-support": "must",
-            "x-optimade-queryable": "must"
+            "x-optimade-queryable": "must",
+            "x-optimade-support": "must"
           },
           "type": {
             "title": "Type",