v0.4.3

Fixed

• temporary_cert_file and temporary_key_file built a malformed file URI on Windows. Both special-cased drive letters by hand, but pathname2url already returns a leading /// for a Windows path, so prefixing file:/// produced six slashes — file://////C:/Users/.../client_cert.pem. A consumer stripping the file:// scheme was left with ////C:/Users/..., which Path reads as \C:\Users\... and cannot open. Both now use Path.as_uri(), which spells this correctly on every platform and needs no branch. The POSIX result is unchanged.