软件版本：slicer 5.0.2
问题描述：编写扩展插件时导入matplotlib包：
from slicer.util import pip_install
pip_install("matplotlib")
import matplotlib.pyplot as plt
出现如下报错：
WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLEOFError(8, 'EOF occurred in violation of protocol (_ssl.c:1129)'))': /simple/matplotlib/
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLEOFError(8, 'EOF occurred in violation of protocol (_ssl.c:1129)'))': /simple/matplotlib/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLEOFError(8, 'EOF occurred in violation of protocol (_ssl.c:1129)'))': /simple/matplotlib/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLEOFError(8, 'EOF occurred in violation of protocol (_ssl.c:1129)'))': /simple/matplotlib/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLEOFError(8, 'EOF occurred in violation of protocol (_ssl.c:1129)'))': /simple/matplotlib/
Could not fetch URL https://pypi.org/simple/matplotlib/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/matplotlib/ (Caused by SSLError(SSLEOFError(8, 'EOF occurred in violation of protocol (_ssl.c:1129)'))) - skipping
ERROR: Could not find a version that satisfies the requirement matplotlib (from versions: none)
ERROR: No matching distribution found for matplotlib
Could not fetch URL https://pypi.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError(SSLEOFError(8, 'EOF occurred in violation of protocol (_ssl.c:1129)'))) - skipping
Traceback (most recent call last):
File "D:/DESKTOP/ex/module3module3.py", line 480, in readPic
pip_install("matplotlib")
File "E:\Slicer 5.0.2\bin\Python\slicer\util.py", line 3431, in pip_install
_executePythonModule('pip', args)
File "E:\Slicer 5.0.2\bin\Python\slicer\util.py", line 3394, in _executePythonModule
logProcessOutput(proc)
File "E:\Slicer 5.0.2\bin\Python\slicer\util.py", line 3363, in logProcessOutput
raise CalledProcessError(retcode, proc.args, output=proc.stdout, stderr=proc.stderr)
subprocess.CalledProcessError: Command '['E:/Slicer 5.0.2/bin/../bin\\PythonSlicer.EXE', '-m', 'pip', 'install', 'matplotlib']' returned non-zero exit status 1.
