build: more Zig 0.15.2 updates (#9217)

- update nixpkgs now that Zig 0.15.2 is available in nixpkgs
- drop hack that worked around compile failures on systems with more
than 32 cores
- enforce patch version of Zig

src/config/Config.zig

@@ -4109,7 +4109,7 @@ pub fn finalize(self: *Config) !void {
     // Clamp our contrast
     self.@"minimum-contrast" = @min(21, @max(1, self.@"minimum-contrast"));
 
-    // Minimmum window size
+    // Minimum window size
     if (self.@"window-width" > 0) self.@"window-width" = @max(10, self.@"window-width");
     if (self.@"window-height" > 0) self.@"window-height" = @max(4, self.@"window-height");