Check markdown table creation in tests

tests/test_calcat_interface2.py

 import numpy as np
 import pytest
+import re
 import xarray as xr
 
 from cal_tools.calcat_interface2 import (
@@ -36,6 +37,10 @@ def test_AGIPD_CalibrationData_metadata():
     assert isinstance(agipd_cd["Offset", "AGIPD00"], SingleConstant)
     assert agipd_cd["Offset", "Q1M2"] == agipd_cd["Offset", "AGIPD01"]
 
+    assert re.search(
+        r"\[2022-\d{2}-\d{2} \d{2}:\d{2}\]\(https://in.xfel.eu/", agipd_cd.markdown_table()
+    )
+
 
 @pytest.mark.requires_gpfs
 def test_AGIPD_merge():