AirNow UTC offset test cases - recent data no longer has bad UTC offsets?

[zmoon]

Noticed in today's scheduled CI run.

FAILED tests/test_airnow.py::test_check_zero_utc_offsets[yesterday-null] - assert 0 > 0
 +  where 0 = <bound method NDFrame._add_numeric_operations.<locals>.sum of 0       False\n1       False\n2       False\n3       False\n4       False\n        ...  \n2022    False\n2023    False\n2024    False\n2025    False\n2026    False\nName: utcoffset, Length: 2027, dtype: bool>()
 +    where <bound method NDFrame._add_numeric_operations.<locals>.sum of 0       False\n1       False\n2       False\n3       False\n4       False\n        ...  \n2022    False\n2023    False\n2024    False\n2025    False\n2026    False\nName: utcoffset, Length: 2027, dtype: bool> = 0       False\n1       False\n2       False\n3       False\n4       False\n        ...  \n2022    False\n2023    False\n2024    False\n2025    False\n2026    False\nName: utcoffset, Length: 2027, dtype: bool.sum
 +      where 0       False\n1       False\n2       False\n3       False\n4       False\n        ...  \n2022    False\n2023    False\n2024    False\n2025    False\n2026    False\nName: utcoffset, Length: 2027, dtype: bool = <bound method Series.isnull of 0      -4.0\n1      -4.0\n2      -4.0\n3      -4.0\n4      -4.0\n       ... \n2022    5.0\n2023    5.0\n2024    5.0\n2025    5.0\n2026    5.0\nName: utcoffset, Length: 2027, dtype: float64>()
 +        where <bound method Series.isnull of 0      -4.0\n1      -4.0\n2      -4.0\n3      -4.0\n4      -4.0\n       ... \n2022    5.0\n2023    5.0\n2024    5.0\n2025    5.0\n2026    5.0\nName: utcoffset, Length: 2027, dtype: float64> = 0      -4.0\n1      -4.0\n2      -4.0\n3      -4.0\n4      -4.0\n       ... \n2022    5.0\n2023    5.0\n2024    5.0\n2025    5.0\n2026    5.0\nName: utcoffset, Length: 2027, dtype: float64.isnull
 +          where 0      -4.0\n1      -4.0\n2      -4.0\n3      -4.0\n4      -4.0\n       ... \n2022    5.0\n2023    5.0\n2024    5.0\n2025    5.0\n2026    5.0\nName: utcoffset, Length: 2027, dtype: float64 =                     time     siteid  BARPR  ...  msa_name  state_name  epa_region\n0    2024-02-18 00:00:00  000010601    NaN  ...       NaN          CC          CA\n1    2024-02-18 00:00:00  000020104    NaN  ...       NaN          CC          CA\n2    2024-02-18 00:00:00  000020301    NaN  ...       NaN          CC          CA\n3    2024-02-18 00:00:00  000020401    NaN  ...       NaN          CC          CA\n4    2024-02-18 00:00:00  000030502    NaN  ...       NaN          CC          CA\n...                  ...        ...    ...  ...       ...         ...         ...\n2022 2024-02-18 00:30:00  DS1010001    NaN  ...       NaN          DS        DSIN\n2023 2024-02-18 00:30:00  DS1010002    NaN  ...       NaN          DS        DSIN\n2024 2024-02-18 00:30:00  DS1010003    NaN  ...       NaN          DS        DSIN\n2025 2024-02-18 00:30:00  DS1010004    NaN  ...       NaN          DS        DSIN\n2026 2024-02-18 00:30:00  DS1010005    NaN  ...       NaN          DS        DSIN\n\n[2027 rows x 58 columns].utcoffset
FAILED tests/test_airnow.py::test_check_zero_utc_offsets[yesterday-leave] - assert not True
 +  where True = Empty DataFrame\nColumns: [siteid, site, longitude]\nIndex: [].empty

[zmoon]

Today though, it didn't fail... so seems to depend on the day. For example, got another failure today in #164 .

[zmoon]

#174 should have addressed this.