Remove changes files that will appear in 0.4.5.7

(0.4.6.1-alpha will come out after the stable releases.)

changes/bug40316

-  o Major bugfixes (security, denial of service):
-    - Fix a bug in appending detached signatures to a pending consensus
-      document that could be used to crash a directory authority.
-      Fixes bug 40316; bugfix on 0.2.2.6-alpha. Tracked as
-      TROVE-2021-002 and CVE-2021-28090.

changes/geoip-2021-03-12

-  o Minor features (geoip data):
-    - We have switched geoip data sources. Previously we shipped
-      IP-to-country mappings from Maxmind's GeoLite2, but in 2019 they
-      changed their licensing term, so we were unable to update them after
-      that point.  We now ship geoip files based on the  IPFire Location
-      Database instead.  (See https://location.ipfire.org/ for more
-      information).  This release updates our geoip files to match the
-      IPFire Location Database as retrieved on 2021/03/12.  Closes
-      ticket 40224.

changes/ticket40286_minimal

-  o Major bugfixes (security, denial of service):
-    - Disable the dump_desc() function that we used to dump unparseable
-      information to disk. It was called incorrectly in several places,
-      in a way that could lead to excessive CPU usage.  Fixes bug 40286;
-      bugfix on 0.2.2.1-alpha. This bug is also tracked as
-      TROVE-2021-001 and CVE-2021-28089.