WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProxyError('Cannot connect to proxy.', NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x00000184C1F31D88>: F
ailed to establish a new connection: [WinError 10061] 由於目標計算機積極拒絕，無法連接。'))': /simple/flask/
切換鏡像源也無法解決問題。
解決方法：
cmd輸入regedit打開注冊表
