Merge branch 'atmosphere/fix_git_protocol' into hotfix-v7.3 (PR #969)

This merge updates the checkout_data_files.sh script to use HTTPS rather than
the unencrypted Git protocol when obtaining the MPAS-Data repository.

On 15 March 2022, GitHub removed support for the unencrypted Git protocol (i.e.,
for obtaining repositories with URLs beginning with git://). As part of the
MPAS-Atmosphere build process, the checkout_data_files.sh script first tries to
obtain the MPAS-Data repository, which contains look-up tables used by physics
schemes, using the URL git://github.com/MPAS-Dev/MPAS-Data.git. Doing so results
in the messages

  *** Trying git to obtain WRF physics tables ***
  Cloning into 'MPAS-Data'...
  fatal: remote error:
    The unauthenticated git protocol on port 9418 is no longer supported.
  Please see https://github.blog/2021-09-01-improving-git-protocol-security-github/ for more information.

The simple solution is to switch to the use of HTTPS when obtaining the
MPAS-Data repository.

Note that, although the checkout_data_files.sh script is no longer able to
obtain the MPAS-Data repository through the unencrypted Git protocol, the
script does implement several fallback methods for obtaining the physics lookup
tables (specifically, as a Subversion (SVN) repository and as a .tar.gz file
using curl).

Author: mgduda

src/core_atmosphere/physics/checkout_data_files.sh

@@ -73,7 +73,7 @@ fi
 which git
 if [ $? -eq 0 ]; then
    echo "*** Trying git to obtain WRF physics tables ***"
-   git clone git://github.com/${github_org}/MPAS-Data.git
+   git clone https://github.com/${github_org}/MPAS-Data.git
    if [ $? -eq 0 ]; then
       cd MPAS-Data
       git checkout v${mpas_vers}