Build dynamic library by default

Using a statically linked dune-uggrid together with the Python bindings leads to hard-to-diagnose crashes and other bugs. This patch therefore enables shared libraries, and adds a lengthy explanation of why this is necessary.

CHANGELOG.md

@@ -9,6 +9,9 @@ SPDX-License-Identifier: LGPL-2.1-or-later
 
 # dune-uggrid 2.10 (2024-09-04)
 
+- `dune-uggrid` now builds a dynamic library by default, because using a shared library
+  together with the Python just-in-time compilation lead to hard-to-diagnose crashes.
+
 * Remove deprecated `AllocEnvMemory` and `FreeEnvMemory`. They were
   wrappers of standard `malloc` and `free`.