chore: format everything

This implicates a change from nixpkgs-fmt to nixfmt. Nixfmt will become
the new standard on nix formatting, sanctioned by the nixpkgs. To verify
that these changes are purely in whitespace, but not semantic:

git diff --ignore-all-space -w HEAD^!

That will only show newline changes, make the diffing somewhat easier.

Signed-off-by: wucke13 <wucke13+github@gmail.com>

overlay.nix

@@ -1,6 +1,5 @@
 final: prev: {
 
-
   #
   ### Actual rosenpass software ###
   #
@@ -27,7 +26,10 @@ final: prev: {
       "marzipan(/marzipan.awk)?"
       "analysis(/.*)?"
     ];
-    nativeBuildInputs = [ final.proverif final.graphviz ];
+    nativeBuildInputs = [
+      final.proverif
+      final.graphviz
+    ];
     CRYPTOVERIF_LIB = final.proverif-patched + "/lib/cryptoverif.pvl";
     installPhase = ''
       mkdir -p $out