r-httpuv: add missing zlib.dev dependency to fix the build

+1
+1
pkgs/development/r-modules/default.nix
··· 342 342 runjags = [ pkgs.jags ]; 343 343 RVowpalWabbit = with pkgs; [ zlib.dev boost ]; 344 344 rzmq = with pkgs; [ zeromq pkg-config ]; 345 + httpuv = [ pkgs.zlib.dev ]; 345 346 clustermq = [ pkgs.zeromq ]; 346 347 SAVE = with pkgs; [ zlib bzip2 icu xz pcre ]; 347 348 sdcTable = with pkgs; [ gmp glpk ];