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_thread.py

@@ -0,0 +1,42 @@
+import threading
+
+from pybind11_tests import thread as m
+
+
+class Thread(threading.Thread):
+    def __init__(self, fn):
+        super().__init__()
+        self.fn = fn
+        self.e = None
+
+    def run(self):
+        try:
+            for i in range(10):
+                self.fn(i, i)
+        except Exception as e:
+            self.e = e
+
+    def join(self):
+        super().join()
+        if self.e:
+            raise self.e
+
+
+def test_implicit_conversion():
+    a = Thread(m.test)
+    b = Thread(m.test)
+    c = Thread(m.test)
+    for x in [a, b, c]:
+        x.start()
+    for x in [c, b, a]:
+        x.join()
+
+
+def test_implicit_conversion_no_gil():
+    a = Thread(m.test_no_gil)
+    b = Thread(m.test_no_gil)
+    c = Thread(m.test_no_gil)
+    for x in [a, b, c]:
+        x.start()
+    for x in [c, b, a]:
+        x.join()