fix(sphinx): recursive dir copy (#4231)

The fix prevents recursive directories copy if `srcdir =
pathlib.Path(args[1])` at
https://github.com/bazel-contrib/rules_python/blob/278664d7/sphinxdocs/sphinxdocs/private/sphinx_build.py#L555
is '.'. which results to
```
   raise DirectorySyncerError(list(self._errors))
DirectorySyncerError: Encountered 1 error(s) during sync:
  - [Errno 36] File name too long: '.worker-in.d/.worker-in.d/.worker-in.d/.worker-in.d/<repeated many times>
```

sphinxdocs/sphinxdocs/private/sphinx_build.py

diff --git a/sphinxdocs/sphinxdocs/private/sphinx_build.py b/sphinxdocs/sphinxdocs/private/sphinx_build.py
index f20fbd6..b01db53 100644
--- a/sphinxdocs/sphinxdocs/private/sphinx_build.py
+++ b/sphinxdocs/sphinxdocs/private/sphinx_build.py
@@ -225,8 +225,11 @@
         """Recursively creates destination directory and submits tasks for its entries."""
         try:
             dest.mkdir(parents=True, exist_ok=True)
+            dest_path = dest.resolve()
             with os.scandir(src) as scanner:
                 for entry in scanner:
+                    if pathlib.Path(entry.path).resolve() == dest_path:
+                        continue
                     c_dest = dest / entry.name
                     c_src = pathlib.Path(entry.path)
                     if entry.is_dir():