Add the experimental FSR patch

[SkewedZeppelin]

See ValveSoftware/wine#116

I don't expect this to be merged, but it is here if anyone wants an easy way of testing:

git clone this repo and cd into it
wget https://github.com/flathub/com.valvesoftware.Steam.CompatibilityTool.Proton-Exp/pull/45.patch
git am 45.patch
flatpak install org.freedesktop.Sdk.Compat.i386 org.freedesktop.Sdk.Extension.toolchain-i386 org.freedesktop.Sdk.Extension.mingw-w64; #choose 20.08 for each
flatpak-builder out com.valvesoftware.Steam.CompatibilityTool.Proton-Exp.yml
flatpak-builder --repo=localrepo out com.valvesoftware.Steam.CompatibilityTool.Proton-Exp.yml --export-only
flatpak build-bundle localrepo proton-fsr.flatpak --runtime com.valvesoftware.Steam.CompatibilityTool.Proton-Exp stable
flatpak install proton-fsr.flatpak

then in Steam choose the Proton-Exp runtime for your game, and set WINE_FULLSCREEN_FSR=1 %command% for the launch arguments.

[flathubbot]

Started test build 54216

[flathubbot]

Build 54216 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/52165/com.valvesoftware.Steam.CompatibilityTool.Proton-Exp.flatpakref

[flathubbot]

Started test build 56504

[flathubbot]

Build 56504 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/54432/com.valvesoftware.Steam.CompatibilityTool.Proton-Exp.flatpakref