Merge JoinMarket-Org/joinmarket-clientserver#1140: Pin python-qrcode to a specific version

f05492110b Pin python-qrcode to a specific version (Kristaps Kaupe)

Pull request description:

  There have been some [takeover of qr.js NPM account recently](https://github.com/zpao/qrcode.react/issues/168). Let's remove potential attack vector here by pinning `qrcode` to a specific (latest) version.

  It seems that PyPI does not allow overwrite of already uploaded files, so, unless PyPI itself is hacked, this is safe, it can't be replaced with something else so easy (although using package hashes would be better, of course).

Top commit has no ACKs.

Tree-SHA512: 34aebae3a875dc780417303649b253c2d4ab40dbbe358fc47dc13913beb1f64e40e670e36fa2eb183f622cf3541cd75ba948f009370a8ffcb93c21d21bfa1262

requirements/gui.txt

@@ -3,7 +3,7 @@ pywin32; platform_system == "Windows"
 # https://bugreports.qt.io/browse/QTBUG-88688
 PySide2!=5.15.0,!=5.15.1,!=5.15.2,!=6.0
 PyQt5!=5.15.0,!=5.15.1,!=5.15.2,!=6.0
-qrcode[pil]
+qrcode[pil]==7.3.1
 https://github.com/sunu/qt5reactor/archive/58410aaead2185e9917ae9cac9c50fe7b70e4a60.zip#egg=qt5reactor
 
 -e ./jmqtui