Docker-Image doesn't build

[GanbaruTobi]

...
x86_64-linux-gnu-gcc: numpy/core/src/multiarray/numpyos.c
numpy/core/src/multiarray/numpyos.c:18:10: fatal error: xlocale.h: No such file or directory
18 | #include <xlocale.h>
| ^~~~~~~~~~~
compilation terminated.

[Kalhama]

Proposed fix #131