Update mergedeep requirement from ~=1.1.1 to >=1.1.1,<1.4.0 (#728)

Updates the requirements on [mergedeep](https://github.com/clarketm/mergedeep) to permit the latest version.
- [Release notes](https://github.com/clarketm/mergedeep/releases)
- [Commits](https://github.com/clarketm/mergedeep/compare/v1.1.1...v1.3.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

setup.py

@@ -46,7 +46,7 @@ setup(
         "aiofiles>=0.4,<0.6",
         "janus~=0.4.0",
         "PyYAML~=5.3",
-        "mergedeep~=1.1.1",
+        "mergedeep>=1.1.1,<1.4.0",
     ],
     entry_points="""
         [console_scripts]