Fix PyQt5 import error by installing libgl1-mesa-glx (#87)

Add installation of `libgl1-mesa-glx` package to `infra/Dockerfile`.

* Update `infra/Dockerfile` to include the installation of
`libgl1-mesa-glx` package.
* Ensure the application starts without the 'libGL.so.1: cannot open
shared object file' error.

---

For more details, open the [Copilot Workspace
session](https://copilot-workspace.githubnext.com/ProjectZeroDays/Project-Red-Sword/pull/87?shareId=c4f884d5-bcb4-452e-8161-8ad32d9e0710).

Author: ProjectZeroDays

frontend/archive_gui.py

@@ -29,4 +29,4 @@ def analyze_sources(self):
     app = QApplication(sys.argv)
     ex = ArchiveGUI()
     ex.show()
-    sys.exit(app.exec_())
+    sys.exit(app.exec_())

infra/Dockerfile

@@ -1,4 +1,3 @@
-
 # Base image
 FROM python:3.9-slim
 
@@ -9,6 +8,7 @@ WORKDIR /app
 COPY . .
 
 # Install dependencies
+RUN apt-get update && apt-get install -y libgl1-mesa-glx
 RUN pip install -r requirements.txt
 
 # Expose application port