mod: bump zterm dependency; add zlog dependency

`zlog` is used to log messages to the log file that is also used by
`serve` by default, making it a single source for all the log messages.

build.zig

@@ -4,6 +4,14 @@ pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
 
+    const zlog = b.dependency("zlog", .{
+        .target = target,
+        .optimize = optimize,
+        .timestamp = false,
+        .stderr = false,
+        .file = "log",
+    });
+
     const zterm = b.dependency("zterm", .{
         .target = target,
         .optimize = optimize,
@@ -17,6 +25,7 @@ pub fn build(b: *std.Build) void {
             .optimize = optimize,
             .imports = &.{
                 .{ .name = "zterm", .module = zterm.module("zterm") },
+                .{ .name = "zlog", .module = zlog.module("zlog") },
                 .{
                     .name = "about",
                     .module = b.createModule(.{