Add option to scripts-dev/lint.sh to only lint files changed since the last git commit (#8472)

This PR makes several changes to the `./scripts-dev/lint.sh` script, which lints the codebase with a number of tools:

* Adds usage information, with `-h` flag to show it. Otherwise it will show when providing an unknown flag.
* Adds option `-d` which will check both staged and unstaged files that have changed since the last commit and add them to the list of files to lint.
  - Note that only files without an extension, or with a `.py` extension will be allowed. This prevents editing bash scripts causing the linters to break on non-python files.
* Improves the print-out of which files/directories are being linted. 

1 files changed, 1 insertions, 3 deletions

diff --git a/setup.py b/setup.py
index 926b1bc86f..08843fe2a3 100755
--- a/setup.py
+++ b/setup.py
@@ -15,12 +15,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
 import glob
 import os
-from setuptools import setup, find_packages, Command
-import sys
 
+from setuptools import Command, find_packages, setup
 
 here = os.path.abspath(os.path.dirname(__file__))