refine source filter

In particular, replace the error prone sourceByRegex filter for the rosenpass derivation with a simple file suffix filter.

flake.nix

@@ -58,11 +58,10 @@
             cargoToml = builtins.fromTOML (builtins.readFile ./rosenpass/Cargo.toml);
 
             # source files relevant for rust
-            src = pkgs.lib.sourceByRegex ./. [
-              "Cargo\\.(toml|lock)"
-              "build.rs"
-              "(src|benches)(/.*\\.(rs|md))?"
-              "rp"
+            src = pkgs.lib.sources.sourceFilesBySuffices ./. [
+              ".lock"
+              ".rs"
+              ".toml"
             ];
 
             # builds a bin path for all dependencies for the `rp` shellscript
@@ -288,7 +287,7 @@
           packages.proof-proverif = pkgs.stdenv.mkDerivation {
             name = "rosenpass-proverif-proof";
             version = "unstable";
-            src = pkgs.lib.sourceByRegex ./. [
+            src = pkgs.lib.sources.sourceByRegex ./. [
               "analyze.sh"
               "marzipan(/marzipan.awk)?"
               "analysis(/.*)?"