Merge pull request #109516 from marsam/update-nodejs-15_x

nodejs-15_x: 15.5.1 -> 15.6.0

pkgs/development/web/nodejs/v15.nix

···
 in
   buildNodejs {
     inherit enableNpm;
-    version = "15.5.1";
-    sha256 = "0qbb4dwgsy1a82ihjxl6r8bj7mwjzb21s720y1rahisd5p69l8ic";
+    version = "15.6.0";
+    sha256 = "1liqkh1gz1h37fln8xr5krbs2mqjn38n3sws2ydvk84wrpfq3prr";
   }