skip netcdf4-python tests that require network connectivity

[boegel]

(created using eb --new-pr)

fix for failing test due to problem with server used in test:

ERROR: runTest (tst_dap.DapTestCase)
testing access of data over http using opendap
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/tmp/vsc40023/easybuild_build/netcdf4python/1.5.5.1/intel-2020b/netcdf4python/netCDF4-1.5.5.1/test/tst_dap.py", line 23, in runTest
    ncfile = netCDF4.Dataset(URL)
  File "netCDF4/_netCDF4.pyx", line 2357, in netCDF4._netCDF4.Dataset.__init__
  File "netCDF4/_netCDF4.pyx", line 1925, in netCDF4._netCDF4._ensure_nc_success
OSError: [Errno -70] NetCDF: DAP server error: b'http://remotetest.unidata.ucar.edu/thredds/dodsC/testdods/testData.nc'

[boegel]

Test report by @boegel

Overview of tested easyconfigs (in order)

• SUCCESS netcdf4-python-1.5.3-foss-2020a-Python-3.8.2.eb
• SUCCESS netcdf4-python-1.5.3-intel-2020a-Python-3.8.2.eb
• SUCCESS netcdf4-python-1.5.5.1-foss-2020b.eb
• SUCCESS netcdf4-python-1.5.5.1-intel-2020b.eb
• SUCCESS netcdf4-python-1.5.7-foss-2021a.eb

Build succeeded for 5 out of 5 (5 easyconfigs in total)
node3126.skitty.os - Linux centos linux 7.9.2009, x86_64, Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz (skylake_avx512), Python 3.6.8
See https://gist.github.com/f201f636273bfe8f73089680cce85fe2 for a full test report.

[verdurin]

Looks fine.

[verdurin]

Going in, thanks @boegel!