bicep/matrix: use synapse package from stable

It's fixed now

flake.lock

@@ -7,11 +7,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1702479765,
-        "narHash": "sha256-wjNYsFhciYoJkZ/FBKvFj55k+vkLbu6C2qYQ7K+s8pI=",
+        "lastModified": 1702569759,
+        "narHash": "sha256-Ze3AdEEsVZBRJ4wn13EZpV1Uubkzi59TkC4j2G9xoFI=",
         "owner": "nix-community",
         "repo": "disko",
-        "rev": "bd8fbc3f274288ac905bcea66bc2a5428abde458",
+        "rev": "98ab91109716871f50ea8cb0e0ac7cc1e1e14714",
         "type": "github"
       },
       "original": {
@@ -80,11 +80,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1702332891,
-        "narHash": "sha256-0OJldHAo405QynEaoo+0VVgPNi454eUpH/VBNEWugtc=",
+        "lastModified": 1702601832,
+        "narHash": "sha256-z+GyetKtwj7ZVZrRcI73N8Xy1B3JGAqDyPniBFRpIgo=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "10cff3acda0e8d514f0ea1b330fc0f6d2bb5f6d0",
+        "rev": "dff64d4ba6e9dc3f0a4ef8737f372a528d5bc8d1",
         "type": "github"
       },
       "original": {
@@ -108,22 +108,6 @@
         "type": "github"
       }
     },
-    "nixpkgs-matrix-buildenv": {
-      "locked": {
-        "lastModified": 1702493286,
-        "narHash": "sha256-qkw063Xoee7NbMhgcIw/eqix4R2mEQbOOMlPzgukgL4=",
-        "owner": "dali99",
-        "repo": "nixpkgs",
-        "rev": "a695ad5fb5eca79e5844c1de0a4c9f5589fcf38c",
-        "type": "github"
-      },
-      "original": {
-        "owner": "dali99",
-        "ref": "synapse-buildenv",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
     "nixpkgs-stable": {
       "locked": {
         "lastModified": 1702148972,
@@ -142,11 +126,11 @@
     },
     "nixpkgs-unstable": {
       "locked": {
-        "lastModified": 1702397419,
-        "narHash": "sha256-CBMSwZHT7GLq2JdOPWAVDBaYFbUHWD1+jPFrYk0JeLM=",
+        "lastModified": 1702635820,
+        "narHash": "sha256-rClms9NTmSL/WIN5VmEccVhUExMkjCrRNswxU9QGNNo=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "73ca2df642228129df7a968bad6499732dbc7ddd",
+        "rev": "02357adddd0889782362d999628de9d309d202dc",
         "type": "github"
       },
       "original": {
@@ -182,7 +166,6 @@
         "grzegorz-clients": "grzegorz-clients",
         "matrix-next": "matrix-next",
         "nixpkgs": "nixpkgs",
-        "nixpkgs-matrix-buildenv": "nixpkgs-matrix-buildenv",
         "nixpkgs-unstable": "nixpkgs-unstable",
         "pvv-calendar-bot": "pvv-calendar-bot",
         "sops-nix": "sops-nix"