remove synapse overlay as there is now a recent enough version upstream

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/92c2e04a475523e723c67ef872d8037379073681?narHash=sha256-yLuz5cz5Z%2Bsn8DRAfNkrd2Z1cV6DaYO9JMrEz4KZo/c%3D' (2025-07-21)
  → 'github:nixos/nixpkgs/9a094440e02a699be5c57453a092a8baf569bdad?narHash=sha256-Vp9K5ol6h0J90jG7Rm4RWZsCB3x7v5VPx588TQ1dkfs%3D' (2025-09-14)
• Updated input 'sops-nix':
    'github:Mic92/sops-nix/2c8def626f54708a9c38a5861866660395bb3461?narHash=sha256-GllP7cmQu7zLZTs9z0J2gIL42IZHa9CBEXwBY9szT0U%3D' (2025-07-15)
  → 'github:Mic92/sops-nix/f77d4cfa075c3de66fc9976b80e0c4fc69e2c139?narHash=sha256-HYnwlbY6RE5xVd5rh0bYw77pnD8lOgbT4mlrfjgNZ0c%3D' (2025-09-16)

flake.lock

@@ -66,11 +66,11 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1753115646,
-        "narHash": "sha256-yLuz5cz5Z+sn8DRAfNkrd2Z1cV6DaYO9JMrEz4KZo/c=",
+        "lastModified": 1757810152,
+        "narHash": "sha256-Vp9K5ol6h0J90jG7Rm4RWZsCB3x7v5VPx588TQ1dkfs=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "92c2e04a475523e723c67ef872d8037379073681",
+        "rev": "9a094440e02a699be5c57453a092a8baf569bdad",
         "type": "github"
       },
       "original": {
@@ -95,11 +95,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1752544651,
-        "narHash": "sha256-GllP7cmQu7zLZTs9z0J2gIL42IZHa9CBEXwBY9szT0U=",
+        "lastModified": 1758007585,
+        "narHash": "sha256-HYnwlbY6RE5xVd5rh0bYw77pnD8lOgbT4mlrfjgNZ0c=",
         "owner": "Mic92",
         "repo": "sops-nix",
-        "rev": "2c8def626f54708a9c38a5861866660395bb3461",
+        "rev": "f77d4cfa075c3de66fc9976b80e0c4fc69e2c139",
         "type": "github"
       },
       "original": {

flake.nix

@@ -41,22 +41,6 @@
         prometheus-exporter = ./config/extra/prometheus-exporter.nix;
       };
       overlays = {
-        matrixSynapseFix = final: prev: {
-          matrix-synapse-unwrapped = prev.matrix-synapse-unwrapped.overrideAttrs (finalAttrs: prevAttrs: rec {
-            version = "1.135.2";
-            src = prev.fetchFromGitHub {
-              owner = "element-hq";
-              repo = "synapse";
-              rev = "v${version}";
-              hash = "sha256-4HAA9Xq4C3DHxz0BgqBitfM4wZwPSEu+IO/OPfHzLVw=";
-            };
-            cargoDeps = final.rustPlatform.fetchCargoVendor {
-              inherit src;
-              hash = "sha256-4J92s6cSgsEIYQpbU6OOLI/USIJX2Gc7UdEHgWQgmXc=";
-            };
-            patches = [];
-          });
-        };
         librespotFixOverlay = final: prev: {
           librespot = (prev.librespot.override { withAvahi = true; }).overrideAttrs (finalAttrs: prevAttr: rec {
             # Build dev branch.
@@ -125,7 +109,6 @@
             sops-nix.nixosModules.sops
             self.nixosModules.prometheus-exporter
             ./config/hosts/matrix
-            { nixpkgs.overlays = [ self.overlays.matrixSynapseFix ]; }
           ];
         };