ci(nix): add Nix build

slides/flake.nix

@@ -0,0 +1,48 @@
+{
+  description = "A basic flake with a shell";
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+  inputs.flake-utils.url = "github:numtide/flake-utils";
+
+  outputs = { self, nixpkgs, nixpkgs-biber, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+        tex = pkgs.texlive.combine {
+          inherit (pkgs.texlive) scheme-small;
+          inherit (pkgs.texlive) latexmk pgf pgfplots tikzsymbols biblatex beamer;
+          inherit (pkgs.texlive) silence appendixnumberbeamer fira fontaxes mwe;
+          inherit (pkgs.texlive) noto csquotes babel helvetic transparent;
+          inherit (pkgs.texlive) xpatch hyphenat wasysym algorithm2e listings;
+          inherit (pkgs.texlive) lstbayes ulem subfigure ifoddpage relsize;
+          inherit (pkgs.texlive) adjustbox media9 ocgx2 biblatex-apa wasy;
+        };
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          packages = [
+            pkgs.bashInteractive
+            pkgs.pdfpc
+          ];
+        };
+        defaultPackage = pkgs.stdenvNoCC.mkDerivation rec {
+          name = "slides";
+          src = self;
+          buildInputs = [
+            pkgs.coreutils
+            tex
+            pkgs.gnuplot
+            pkgs.biber
+          ];
+          phases = [ "unpackPhase" "buildPhase" "installPhase" ];
+          buildPhase = ''
+            export PATH="${pkgs.lib.makeBinPath buildInputs}";
+            export HOME=$(pwd)
+            latexmk -pdflatex -shell-escape slides.tex
+          '';
+          installPhase = ''
+            mkdir -p $out
+            cp slides.pdf $out/
+          '';
+        };
+      });
+}

slides/slides.tex

@@ -57,7 +57,7 @@
 \graphicspath{{logos}{images}}
 \pgfplotsset{height=6cm, % only if needed
 	width=12cm,
-	compat=1.17,
+	compat=1.18,
 	legend style = {fill = black, draw = white},
 	contour/every contour label/.style={
 			every node/.style={mapped color!50!black,fill=black}}