restore latest working PyQt5 version

Author: gilesknap

setup.cfg

@@ -24,7 +24,7 @@ package_dir =
     =src
 
 setup_requires =
-    "setuptools_scm[toml]">=6.2
+    setuptools_scm[toml]>=6.2
 
 # Specify any package dependencies below.
 include_package_data = True
@@ -33,7 +33,7 @@ install_requires =
     # dls-pmaclib @ https://github.com/DiamondLightSource/dls-pmac-lib/archive/refs/tags/3.0.0.zip
     dls-pmaclib >= 3.0.1-beta1
     numpy
-    pyqt5 == 5.12.2
+    pyqt5 == 5.15.7
     pythonqwt
     mock