Update mailchecker requirement from ~=4.1.19 to ~=5.0.0 (#106)

Updates the requirements on [mailchecker](https://github.com/FGRibreau/mailchecker) to permit the latest version.
- [Release notes](https://github.com/FGRibreau/mailchecker/releases)
- [Changelog](https://github.com/FGRibreau/mailchecker/blob/master/CHANGELOG.md)
- [Commits](FGRibreau/mailchecker@v4.1.19...v5.0.0)

---
updated-dependencies:
- dependency-name: mailchecker
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -1,5 +1,5 @@
 ftfy ~= 6.0.0
-mailchecker ~= 4.1.19
+mailchecker ~= 5.0.0
 phonenumbers ~= 8.12.53
 python-dateutil ~= 2.8.2
 python-fsutil ~= 0.6.1

setup.py

@@ -95,7 +95,7 @@
     ],
     install_requires=[
         "ftfy >= 6.0.0, < 7.0.0",
-        "mailchecker >= 4.1.0, < 5.0.0",
+        "mailchecker >= 4.1.0, < 6.0.0",
         "phonenumbers >= 8.12.0, < 9.0.0",
         "python-dateutil >= 2.8.0, < 3.0.0",
         "python-fsutil >= 0.6.0, < 1.0.0",