Deprecated methods in wave_resource.py

[kbrunik]

/HOPP/hopp/simulation/technologies/resource/wave_resource.py:102): FutureWarning: 'H' is deprecated and will be removed in a future version, please use 'h' instead.
  data_df = df.resample("H").mean()


/HOPP/hopp/simulation/technologies/resource/wave_resource.py:110](https://file+.vscode-resource.vscode-cdn.net/Users/kbrunik/github/HOPP/hopp/simulation/technologies/resource/wave_resource.py:110): FutureWarning: 'H' is deprecated and will be removed in a future version, please use 'h' instead.
  missing_time = pd.date_range(last_hour + pd.Timedelta(hours=1),periods=missing_hours, freq='H')


/HOPP/hopp/simulation/technologies/resource/wave_resource.py:112](https://file+.vscode-resource.vscode-cdn.net/Users/kbrunik/github/HOPP/hopp/simulation/technologies/resource/wave_resource.py:112): FutureWarning: The behavior of DataFrame concatenation with empty or all-NA entries is deprecated. In a future version, this will no longer exclude empty or all-NA columns when determining the result dtypes. To retain the old behavior, exclude the relevant entries before the concat operation.
  data_df = pd.concat([data_df, missing_rows]).sort_index()


/HOPP/hopp/simulation/technologies/resource/wave_resource.py:113](https://file+.vscode-resource.vscode-cdn.net/Users/kbrunik/github/HOPP/hopp/simulation/technologies/resource/wave_resource.py:113): FutureWarning: DataFrame.fillna with 'method' is deprecated and will raise in a future version. Use obj.ffill() or obj.bfill() instead.
  data_df = data_df.fillna(method='ffill') # forward fill