[C++] Update linting and formatting scripts to specify python3 in shebang line #29388
Description
Currently the script in cpp/build-support/run_clang_format.py requires modifying to run on any machines/environments where the shebang line #!/usr/bin/env python finds the system python2 instead of python3.
Updating the shebang line to read python3 instead of python would fix this.
Reporter: Nicola Crane / @thisisnic
Assignee: Nicola Crane / @thisisnic
PRs and other links:
Note: This issue was originally created as ARROW-13759. Please see the migration documentation for further details.