Logging (#8)

- Add `Logger`, `Config`
- Back to `nixos-unstable`
- `nix flake update`

flake.lock

@@ -2,11 +2,11 @@
   "nodes": {
     "crane": {
       "locked": {
-        "lastModified": 1733016477,
-        "narHash": "sha256-Hh0khbqBeCtiNS0SJgqdWrQDem9WlPEc2KF5pAY+st0=",
+        "lastModified": 1733286231,
+        "narHash": "sha256-mlIDSv1/jqWnH8JTiOV7GMUNPCXL25+6jmD+7hdxx5o=",
         "owner": "ipetkov",
         "repo": "crane",
-        "rev": "76d64e779e2fbaf172110038492343a8c4e29b55",
+        "rev": "af1556ecda8bcf305820f68ec2f9d77b41d9cc80",
         "type": "github"
       },
       "original": {
@@ -56,16 +56,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1720535198,
-        "narHash": "sha256-zwVvxrdIzralnSbcpghA92tWu2DV2lwv89xZc8MTrbg=",
+        "lastModified": 1733212471,
+        "narHash": "sha256-M1+uCoV5igihRfcUKrr1riygbe73/dzNnzPsmaLCmpo=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "205fd4226592cc83fd4c0885a3e4c9c400efabb5",
+        "rev": "55d15ad12a74eb7d4646254e13638ad0c4128776",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-23.11",
+        "ref": "nixos-unstable",
         "repo": "nixpkgs",
         "type": "github"
       }