Merge branch 'build/nixpkgs-in-lock-file' into 'master'

Use the lock file to specify the version of nixpkgs

See merge request laiser/caisar!100

flake.lock

@@ -43,10 +43,8 @@
         "type": "github"
       },
       "original": {
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "5148520bfab61f99fd25fb9ff7bfbb50dad3c9db",
-        "type": "github"
+        "id": "nixpkgs",
+        "type": "indirect"
       }
     },
     "root": {

flake.nix

@@ -3,7 +3,7 @@
   inputs = {
     flake-utils.url = "github:numtide/flake-utils";
     nix-filter.url = "github:numtide/nix-filter";
-    nixpkgs.url = github:NixOS/nixpkgs/5148520bfab61f99fd25fb9ff7bfbb50dad3c9db;
+    nixpkgs.url = "nixpkgs";
   };
   outputs =
     { self