Alibi Detect Server libGL.so failed to find in image

[ukclivecox]

Describe the bug

[E 200924 12:29:23 plot:39] Importing plotly failed. Interactive plots will not work.
Traceback (most recent call last):
  File "/usr/lib64/python3.6/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib64/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/opt/app-root/src/adserver/__main__.py", line 9, in <module>
    from adserver.od_model import AlibiDetectOutlierModel
  File "/opt/app-root/src/adserver/od_model.py", line 7, in <module>
    from adserver.base import CEModel
  File "/opt/app-root/src/adserver/base/__init__.py", line 2, in <module>
    from .alibi_model import AlibiDetectModel
  File "/opt/app-root/src/adserver/base/alibi_model.py", line 4, in <module>
    from alibi_detect.utils.saving import load_detector, Data
  File "/opt/app-root/lib/python3.6/site-packages/alibi_detect/__init__.py", line 1, in <module>
    from . import ad, cd, metrics, models, od, utils
  File "/opt/app-root/lib/python3.6/site-packages/alibi_detect/od/__init__.py", line 10, in <module>
    from .llr import LLR
  File "/opt/app-root/lib/python3.6/site-packages/alibi_detect/od/llr.py", line 13, in <module>
    from alibi_detect.utils.perturbation import mutate_categorical
  File "/opt/app-root/lib/python3.6/site-packages/alibi_detect/utils/perturbation.py", line 1, in <module>
    import cv2
  File "/opt/app-root/lib/python3.6/site-packages/cv2/__init__.py", line 5, in <module>
    from .cv2 import *
ImportError: libGL.so.1: cannot open shared object file: No such file or directory

To reproduce

Build seldonio/alibi-detect-server:1.3.0-dev