fswebcam: fix src url

pkgs/os-specific/linux/fswebcam/default.nix

···
 
 stdenv.mkDerivation rec {
   pname = "fswebcam";
-  version = "2020-07-25";
+  version = "20200725";
 
   src = fetchurl {
-    url = "https://www.sanslogic.co.uk/fswebcam/files/fswebcam-${lib.replaceStrings ["."] [""] version}.tar.gz";
+    url = "https://www.sanslogic.co.uk/fswebcam/files/fswebcam-${version}.tar.gz";
     sha256 = "1dazsrcaw9s30zz3jpxamk9lkff5dkmflp1s0jjjvdbwa0k6k6ii";
   };