format cls timestamp string

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "244fdb2ca7e1595ca468c0f56bb8936b1fa6efce78ace99461e8ca813fe7114f"
+            "sha256": "f26715f8bf90baafbc19577704c69a2e335d990584d26a304e4e8604004f18a4"
         },
         "pipfile-spec": 6,
         "requires": {},
@@ -14,6 +14,14 @@
         ]
     },
     "default": {
+        "arrow": {
+            "hashes": [
+                "sha256:05caf1fd3d9a11a1135b2b6f09887421153b94558e5ef4d090b567b47173ac2b",
+                "sha256:d622c46ca681b5b3e3574fcb60a04e5cc81b9625112d5fb2b44220c36c892177"
+            ],
+            "index": "pypi",
+            "version": "==1.2.2"
+        },
         "asttokens": {
             "hashes": [
                 "sha256:0844691e88552595a6f4a4281a9f7f79b8dd45ca4ccea82e5e05b4bbdb76705c",
@@ -209,6 +217,14 @@
             "markers": "python_version >= '3.6'",
             "version": "==2.12.0"
         },
+        "python-dateutil": {
+            "hashes": [
+                "sha256:0123cacc1627ae19ddf3c27a5de5bd67ee4586fbdd6440d9748f8abb483d3e86",
+                "sha256:961d03dc3453ebbc59dbdea9e4e11c5651520a876d0f4db161e8674aae935da9"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==2.8.2"
+        },
         "python-dotenv": {
             "hashes": [
                 "sha256:b7e3b04a59693c42c36f9ab1cc2acc46fa5df8c78e178fc33a8d4cd05c8d498f",