Set map_variables=True in pvgis_tmy functions

[AdamRJensen]

• Closes #xxxx
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Change map_variables to default to True instead of None and remove the warning in get_pvgis_tmy and read_pvgis_tmy. See discussion here: #1245 (comment)

Note, the map_variables parameter was introduced in #1268.

Test failures seem unrelated.

[kandersolar]

LGTM, thanks @AdamRJensen!