Resolve "release v1.4.0"

Closes #317 (closed)

test/test_helpers/test_tables.py

+import pandas as pd
+import numpy as np
+
+from mlair.helpers import tables
+
+
+class TestTables:
+
+    def test_create_column_format_for_tex(self):
+        df = pd.DataFrame(np.ones((2, 1)))
+        df_col = tables.create_column_format_for_tex(df)  # len: 1+1
+        assert df_col == 'lr'
+        assert len(df_col) == 2
+        df = pd.DataFrame(np.ones((2, 2)))
+        df_col = tables.create_column_format_for_tex(df)  # len: 2+1
+        assert df_col == 'lcr'
+        assert len(df_col) == 3
+        df = pd.DataFrame(np.ones((2, 3)))
+        df_col = tables.create_column_format_for_tex(df)  # len: 3+1
+        assert df_col == 'lccr'
+        assert len(df_col) == 4