Update and fix Linux CI builds

- Updating to remove usage of a deprecated enum in boost, we also needed
  to update the version of boost used in the Linux build, so now we use
  Ubuntu 22 which provides boost 1.74
- Updating Ubuntu must have updated the default C++ standard used when
  building TGUI, because TGUI started throwing compiler errors coming
  from conditional code that is for >C++17 only. I added an environment
  variable to install-TGUI.sh so it will build with C++14 to match the
  standard for the cboe build on linux
- some CI runs were throwing network errors from apt-get install, so I
  added apt-get update as a precaution. Maybe less builds will fail from
  network errors now?

.github/workflows/ci.yml

@@ -181,7 +181,7 @@
 		# 	]
 		# },
 		linux: {
-			runs-on: ubuntu-20.04,
+			runs-on: ubuntu-22.04,
 			steps: [
 				{
 					name: checkout,
@@ -190,7 +190,7 @@
 				},
 				{
 					name: install dependencies,
-					run: 'sudo apt-get install scons libxml2-utils zlib1g libsfml-dev libboost-all-dev zenity'
+					run: 'sudo apt-get update && sudo apt-get install scons libxml2-utils zlib1g libsfml-dev libboost-all-dev zenity'
 				},
 				{
 					name: install TGUI,