Fix AppImage not containing all SSL dependencies (#4400)

This means the AppImage is built on Ubuntu 20.04 using Qt 5.12

.docker/Dockerfile-ubuntu-22.04-package

@@ -1,8 +1,21 @@
 FROM chatterino-ubuntu-22.04-build
 
-ADD .CI /src/.CI
+# In CI, this is set from the aqtinstall action
+ENV Qt5_DIR=/opt/qt515
 
 WORKDIR /src/build
 
+ADD .CI /src/.CI
+
+# Install dependencies necessary for AppImage packaging
+RUN apt-get update && apt-get -y install --no-install-recommends \
+        curl \
+        libxcb-shape0 \
+        libfontconfig1 \
+        file
+
 # package deb
 RUN ./../.CI/CreateUbuntuDeb.sh
+
+# package appimage
+RUN ./../.CI/CreateAppImage.sh