Double asterisks in path used by PMP was not supported by xarray

PMP used double asterisks in its file paths to expand directories and files, for example, the `infile: /global/cfs/projectdirs/m4931/gsharing/css03_data/CMIP6/CMIP/INM/INM-CM5-0/amip/r1i1p1f1/**/ta_*12.nc` was used, then `xr.open_mfdataset` was used to open it. It seemed that xarray does not support it. The `glob` expansion is needed before the file was opened by xarray.

```
start and end are 1981-01 2005-12 │
│ variable list: ['ta'] │
│ ver: v20260319 │
│ var: ta │
│ infile: /global/cfs/projectdirs/m4931/gsharing/css03_data/CMIP6/CMIP/INM/INM-CM5-0/amip/r1i1p1f1/**/ta_*12.nc │
│ outfile: │
│ /pscratch/sd/m/minxu/mytest_ref_2026-03-14/config/scratch/pmp/annual-cycle/09e02b3b305852e52faac1746181d4d39d223e8c/ta_IN │
│ M-CM5-0_amip_r1i1p1f1_clims.nc │
│ outfilename: None │
│ outpath: None │
│ ver: v20260319 │
│ infilename: ta_*12.nc │
│ Traceback (most recent call last): │
│ File │
│ "/pscratch/sd/m/minxu/mytest_ref_2026-03-14/config/software/conda/pmp-a0cd98ec96f7c858f788439a4f0b4951fe2d7a55/bin/pcmdi_ │
│ compute_climatologies.py", line 91, in │
│ calculate_climatology( │
│ File │
│ "/pscratch/sd/m/minxu/mytest_ref_2026-03-14/config/software/conda/pmp-a0cd98ec96f7c858f788439a4f0b4951fe2d7a55/lib/python │
│ 3.10/site-packages/pcmdi_metrics/mean_climate/lib/calculate_climatology.py", line 33, in calculate_climatology │
│ d = xcdat_open(infile, data_var=var) │
│ File │
│ "/pscratch/sd/m/minxu/mytest_ref_2026-03-14/config/software/conda/pmp-a0cd98ec96f7c858f788439a4f0b4951fe2d7a55/lib/python │
│ 3.10/site-packages/pcmdi_metrics/io/xcdat_openxml.py", line 56, in xcdat_open │
│ ds = xc.open_mfdataset( │
│ File │
│ "/pscratch/sd/m/minxu/mytest_ref_2026-03-14/config/software/conda/pmp-a0cd98ec96f7c858f788439a4f0b4951fe2d7a55/lib/python │
│ 3.10/site-packages/xcdat/dataset.py", line 234, in open_mfdataset │
│ ds = xr.open_mfdataset( │
│ File │
│ "/pscratch/sd/m/minxu/mytest_ref_2026-03-14/config/software/conda/pmp-a0cd98ec96f7c858f788439a4f0b4951fe2d7a55/lib/python │
│ 3.10/site-packages/xarray/backends/api.py", line 1597, in open_mfdataset │
│ raise OSError("no files to open") │
│ OSError: no files to open │
│ │
│ stderr: None
```