[S1.OSV] fixed bug in searching STEP repository

[johntruckenbrodt]

The OSV files on https://step.esa.int/auxdata/orbits/Sentinel-1/ are sorted by year and month. S1.OSV.catch used to stop searching if the start date of one file on a month's folder (URL) exceeded the defined stop date. In some cases however, the right file would be found in the next month's folder.

# scene
S1B_IW_GRDH_1SDV_20210302T061134_20210302T061159_025832_0314AC_52D5.SAFE

# last file for month 2021-02 (not matching the scene)
2021/02/S1B_OPER_AUX_POEORB_OPOD_20210323T111606_V20210302T225942_20210304T005942.EOF.zip

# needed file
2021/03/S1B_OPER_AUX_POEORB_OPOD_20210322T111543_V20210301T225942_20210303T005942.EOF.zip