Revert "build: nix flake update fenix"

This reverts commit aa3ef5011b.

This fixes `nix build .#deltachat-rpc-server-armeabi-v7a-android`.

flake.lock

@@ -48,11 +48,11 @@
         "rust-analyzer-src": "rust-analyzer-src"
       },
       "locked": {
-        "lastModified": 1729578683,
-        "narHash": "sha256-h0Wmvrkadbyi3IJXFLPi+QyYjCAKDr2xQ6dLxlQ8cXY=",
+        "lastModified": 1714112748,
+        "narHash": "sha256-jq6Cpf/pQH85p+uTwPPrGG8Ky/zUOTwMJ7mcqc5M4So=",
         "owner": "nix-community",
         "repo": "fenix",
-        "rev": "d66cda53e8193a878742dcadb5bb75f4df7c3c0a",
+        "rev": "3ae4b908a795b6a3824d401a0702e11a7157d7e1",
         "type": "github"
       },
       "original": {
@@ -166,11 +166,11 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1729256560,
-        "narHash": "sha256-/uilDXvCIEs3C9l73JTACm4quuHUsIHcns1c+cHUJwA=",
+        "lastModified": 1713895582,
+        "narHash": "sha256-cfh1hi+6muQMbi9acOlju3V1gl8BEaZBXBR9jQfQi4U=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "4c2fcb090b1f3e5b47eaa7bd33913b574a11e0a0",
+        "rev": "572af610f6151fd41c212f897c71f7056e3fb518",
         "type": "github"
       },
       "original": {
@@ -222,11 +222,11 @@
     "rust-analyzer-src": {
       "flake": false,
       "locked": {
-        "lastModified": 1729533545,
-        "narHash": "sha256-A/AuEWcGwwjpfBCZqWDNNg5GwYrJduzLvlMe+A7xG5U=",
+        "lastModified": 1714031783,
+        "narHash": "sha256-xS/niQsq1CQPOe4M4jvVPO2cnXS/EIeRG5gIopUbk+Q=",
         "owner": "rust-lang",
         "repo": "rust-analyzer",
-        "rev": "de2ff17bc513807412d7bbaba1d995a774938583",
+        "rev": "56bee2ddafa6177b19c631eedc88d43366553223",
         "type": "github"
       },
       "original": {