Use {} for better performance in dict() (#8751)

### Description
Follow-up for #8748 and so on (I'll combine these changes in future 👍)

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [ ] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

Signed-off-by: Benedikt Johannes <[email protected]>
Co-authored-by: Eric Kerfoot <[email protected]>

Author: benediktjohannes

monai/apps/auto3dseg/auto_runner.py

@@ -229,7 +229,7 @@ def __init__(
             input = os.path.join(os.path.abspath(work_dir), "input.yaml")
             logger.info(f"Input config is not provided, using the default {input}")
 
-        self.data_src_cfg = dict()
+        self.data_src_cfg = {}
         if isinstance(input, dict):
             self.data_src_cfg = input
         elif isinstance(input, str) and os.path.isfile(input):