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/tests/test_embed/test_interpreter.py

@@ -0,0 +1,14 @@
+import sys
+
+from widget_module import Widget
+
+
+class DerivedWidget(Widget):
+    def __init__(self, message):
+        super().__init__(message)
+
+    def the_answer(self):
+        return 42
+
+    def argv0(self):
+        return sys.argv[0]