Bump opower to 0.8.9

[tronikos]

Breaking change

Proposed change

tronikos/opower@v0.8.8...v0.8.9
Because the library bump is a "breaking change" I had to change handling the exceptions in the same PR.
And because I added py.typed in the library, I had to fix mypy

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• This PR fixes or closes issue: fixes No AMI UtilityAccounts found #136863
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[thecode]

@tronikos can you fix the mypy failures?

Error: homeassistant/components/opower/sensor.py:100: error: Argument "value_fn" to "OpowerEntityDescription" has incompatible type "Callable[[Forecast], date]"; expected "Callable[[Forecast], str | float]"  [arg-type]
Error: homeassistant/components/opower/sensor.py:100: error: Incompatible return value type (got "date", expected "str | float")  [return-value]
Error: homeassistant/components/opower/sensor.py:108: error: Argument "value_fn" to "OpowerEntityDescription" has incompatible type "Callable[[Forecast], date]"; expected "Callable[[Forecast], str | float]"  [arg-type]
Error: homeassistant/components/opower/sensor.py:108: error: Incompatible return value type (got "date", expected "str | float")  [return-value]
Error: homeassistant/components/opower/sensor.py:172: error: Argument "value_fn" to "OpowerEntityDescription" has incompatible type "Callable[[Forecast], date]"; expected "Callable[[Forecast], str | float]"  [arg-type]
Error: homeassistant/components/opower/sensor.py:172: error: Incompatible return value type (got "date", expected "str | float")  [return-value]
Error: homeassistant/components/opower/sensor.py:180: error: Argument "value_fn" to "OpowerEntityDescription" has incompatible type "Callable[[Forecast], date]"; expected "Callable[[Forecast], str | float]"  [arg-type]
Error: homeassistant/components/opower/sensor.py:180: error: Incompatible return value type (got "date", expected "str | float")  [return-value]

[tronikos]

Merging because the failure is in unrelated tests/components/airtouch5/test_cover.py