fix: Only include *.tif files in Tiff file paths for RCM

[jthetzel]

This minor pull request changes the RCM load digital number glob pattern from imagery/* to imagery/*.tif. This aligns with the xradarsat2 library ( https://github.com/umr-lops/xradarsat2/blob/main/src/xradarsat2/radarSat2_tiff_reader.py#L24 ). Colleagues open the .tif RCM images in ArcMap, which creates .xml metadata files in the imagery directory. These .xml files resulted in errors like:

CPLE_OpenFailedError: '/content/drive/MyDrive/20230306/RCM2_OK2203930_PK2468015_1_SC50MB_20230306_094918_HH_HV_GRD/RCM2_OK2203930_PK2468015_1_SC50MB_20230306_094918_HH_HV_GRD/imagery/2468015_1_HH.tif.aux.xml' not recognized as a supported file format.

[agrouaze]

@jthetzel Thanks for this bug fix!