fix: Update the copyright header for readthedocs (#341)

The current one references 2017, and it is confusing since the website
may be perceived as outdated one

---------

Co-authored-by: Till Hoffmann <[email protected]>
Co-authored-by: David Ankin <[email protected]>

Author: 3 people

conf.py

@@ -52,7 +52,7 @@
 
 # General information about the project.
 project = "testcontainers"
-copyright = "2017, Sergey Pirogov"  # noqa: A001
+copyright = "2017-2024, Sergey Pirogov and Testcontainers Python contributors"  # noqa: A001
 author = "Sergey Pirogov"
 
 # The version info for the project you're documenting, acts as replacement for