Hardcopy of pybind11 instead of using git submodules (#552)

* removed pybind as submodule
* added hardcopy of pybind11 2.10.0
* rename pybind11 folder to avoid conflicts when changing branch

Co-authored-by: Dhanya Thattil <dhanya.thattil@psi.ch>

libs/pybind/pybind11/_version.py

@@ -0,0 +1,12 @@
+from typing import Union
+
+
+def _to_int(s: str) -> Union[int, str]:
+    try:
+        return int(s)
+    except ValueError:
+        return s
+
+
+__version__ = "2.10.0"
+version_info = tuple(_to_int(s) for s in __version__.split("."))