Update pyqt5 requirement from ~=2.4.0 to ~=5.15.10 in /scripts

Updates the requirements on [pyqt5](https://www.riverbankcomputing.com/software/pyqt/) to permit the latest version.

---
updated-dependencies:
- dependency-name: pyqt5
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

scripts/RGM_requirements.txt

@@ -1,2 +1,2 @@
 PyQt5~=2.4.0
-PyQt5~=5.14.1
+PyQt5~=5.15.10