treewide: fix redirected urls (run 3)

Related:
 - 9fc5e7e473
 - 593e11fd94
 - 508ae42a0f

Since the last time I ran this script, the Repology API changed, so I had to
adapt the script used in the previous PR. The new API should be more robust, so
overall this is a positive (no more grepping the error messages for our relevant
data but just a nice json structure).

Here's the new script I used:

```sh
curl https://repology.org/api/v1/repository/nix_unstable/problems \
   | jq -r '.[] | select(.type == "homepage_permanent_https_redirect") | .data | "s@\(.url)@\(.target)@"' \
   | sort | uniq | tee script.sed
find -name '*.nix' | xargs -P4 -- sed -f script.sed -i
```

I will also add this script to `maintainers/scripts`.

pkgs/development/libraries/libevent/default.nix

@@ -53,7 +53,7 @@ stdenv.mkDerivation rec {
       and then add or remove events dynamically without having to change
       the event loop.
     '';
-    homepage = "http://libevent.org/";
+    homepage = "https://libevent.org/";
     license = licenses.bsd3;
     platforms = platforms.all;
   };