Added Test for BG13

[shaikhibrahim2000]

Description

This PR adds BG13, ensuring that kWh readings are correctly converted to metric tons of CO₂ (MTon CO₂) within meterDatakWhGroups. The test validates:

• 1-day bars for 15 + 20-minute reading intervals.
• Correct application of the 7.09e-4 conversion factor (kWh → MTon CO₂).
• Proper handling of unbounded start/end times (-inf to +inf).
• Support for relevant unit conversions (u2, u10, u11, u12) and chained transformations (c11, c12, c13).

This update improves OED’s metric ton CO₂ calculations and ensures consistency with Electric_Utility-based unit conversions.

Partly addresses #962

Type of change

• Note merging this changes the database configuration.
• This change requires a documentation update

Checklist

• I have followed the OED pull request ideas
• I have removed text in ( ) from the issue request
• You acknowledge that every person contributing to this work has signed the OED Contributing License Agreement and each author is listed in the Description section.

Limitations

No known limitations.

[huss]

@shaikhibrahim2000 In the description, the checkbox for the CLA is checked but our records do not indicate you signed the CLA. Let us know if you think that is wrong or please do this via the link in that item above.

[shaikhibrahim2000]

@shaikhibrahim2000 In the description, the checkbox for the CLA is checked but our records do not indicate you signed the CLA. Let us know if you think that is wrong or please do this via the link in that item above.

@huss I have signed the CLA.

[huss]

Thanks to @shaikhibrahim2000 for their first contribution to OED. Testing and review found the test case works as expected. I have made a couple of small comments on style to address.

[huss]

Thanks to @shaikhibrahim2000 on the quick changes. Everything looks good. Congratulations on your first accepted work for OED.