Remove unused datestamp definition

Author: ccoffin

schema/CVE_Record_Format.json

@@ -82,12 +82,6 @@
             "minLength": 2,
             "maxLength": 32
         },
-        "datestamp": {
-            "description": "Date/time format based on RFC3339 and ISO ISO8601.",
-            "type": "string",
-            "format": "date",
-            "pattern": "^((2000|2400|2800|(19|2[0-9](0[48]|[2468][048]|[13579][26])))-02-29)|(((19|2[0-9])[0-9]{2})-02-(0[1-9]|1[0-9]|2[0-8]))|(((19|2[0-9])[0-9]{2})-(0[13578]|10|12)-(0[1-9]|[12][0-9]|3[01]))|(((19|2[0-9])[0-9]{2})-(0[469]|11)-(0[1-9]|[12][0-9]|30))$"
-        },
         "timestamp": {
             "type": "string",
             "description": "Date/time format based on RFC3339 and ISO ISO8601, with an optional timezone in the format 'yyyy-MM-ddTHH:mm:ss[+-]ZH:ZM'. If timezone offset is not given, GMT (+00:00) is assumed.",