Bump dnspython from 2.4.2 to 2.6.1 (#2264)

* Bump dnspython from 2.4.2 to 2.6.1

Bumps [dnspython](https://github.com/rthalley/dnspython) from 2.4.2 to 2.6.1.
- [Release notes](https://github.com/rthalley/dnspython/releases)
- [Changelog](https://github.com/rthalley/dnspython/blob/main/doc/whatsnew.rst)
- [Commits](https://github.com/rthalley/dnspython/compare/v2.4.2...v2.6.1)

---
updated-dependencies:
- dependency-name: dnspython
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

* Update dnspython==2.6.1

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: JonnyWong16 <9099342+JonnyWong16@users.noreply.github.com>

[skip ci]

lib/dns/rdataset.py

@@ -28,6 +28,7 @@ import dns.name
 import dns.rdata
 import dns.rdataclass
 import dns.rdatatype
+import dns.renderer
 import dns.set
 import dns.ttl
 
@@ -45,7 +46,6 @@ class IncompatibleTypes(dns.exception.DNSException):
 
 
 class Rdataset(dns.set.Set):
-
     """A DNS rdataset."""
 
     __slots__ = ["rdclass", "rdtype", "covers", "ttl"]
@@ -316,11 +316,9 @@ class Rdataset(dns.set.Set):
             want_shuffle = False
         else:
             rdclass = self.rdclass
-        file.seek(0, io.SEEK_END)
         if len(self) == 0:
             name.to_wire(file, compress, origin)
-            stuff = struct.pack("!HHIH", self.rdtype, rdclass, 0, 0)
-            file.write(stuff)
+            file.write(struct.pack("!HHIH", self.rdtype, rdclass, 0, 0))
             return 1
         else:
             l: Union[Rdataset, List[dns.rdata.Rdata]]
@@ -331,16 +329,9 @@ class Rdataset(dns.set.Set):
                 l = self
             for rd in l:
                 name.to_wire(file, compress, origin)
-                stuff = struct.pack("!HHIH", self.rdtype, rdclass, self.ttl, 0)
-                file.write(stuff)
-                start = file.tell()
-                rd.to_wire(file, compress, origin)
-                end = file.tell()
-                assert end - start < 65536
-                file.seek(start - 2)
-                stuff = struct.pack("!H", end - start)
-                file.write(stuff)
-                file.seek(0, io.SEEK_END)
+                file.write(struct.pack("!HHI", self.rdtype, rdclass, self.ttl))
+                with dns.renderer.prefixed_length(file, 2):
+                    rd.to_wire(file, compress, origin)
             return len(self)
 
     def match(
@@ -373,7 +364,6 @@ class Rdataset(dns.set.Set):
 
 @dns.immutable.immutable
 class ImmutableRdataset(Rdataset):  # lgtm[py/missing-equals]
-
     """An immutable DNS rdataset."""
 
     _clone_class = Rdataset