Remove git-remote-branch and nyan plugins (deprecated)

plugins/git-remote-branch/README.md

-# git-remote-branch plugin
-
-This plugin adds completion for [`grb`](https://github.com/webmat/git_remote_branch),
-or `git_remote_branch`.
-
-To use it, add `git-remote-branch` to the plugins array of your zshrc file:
-
-```zsh
-plugins=(... git-remote-branch)
-```
-
-## Deprecation
-
-[git_remote_branch was archived in 2018](https://github.com/webmat/git_remote_branch#archived),
-meaning it's not actively maintained anymore. Use at your own risk.

plugins/git-remote-branch/git-remote-branch.plugin.zsh

-_git_remote_branch() {
-  ref=$(git symbolic-ref HEAD 2> /dev/null)
-  if [[ -n $ref ]]; then
-    if (( CURRENT == 2 )); then
-      # first arg: operation
-      compadd create publish rename delete track
-    elif (( CURRENT == 3 )); then
-      # second arg: remote branch name
-      remotes=`git remote | tr '\n' '|' | sed "s/\|$//g"`
-      compadd `git branch -r | grep -v HEAD | sed "s/$remotes\///" | sed "s/ //g"`
-    elif (( CURRENT == 4 )); then
-      # third arg: remote name
-      compadd `git remote`
-    fi
-  else;
-    _files
-  fi
-}
-compdef _git_remote_branch grb

plugins/nyan/README.md

-# Nyan plugin
-
-This plugin adds a command to display [Nyan Cat](https://en.wikipedia.org/wiki/Nyan_Cat) right inside your terminal.
-
-**Plugin is deprecated**. Check [official repo](https://github.com/klange/nyancat) for more information.
\ No newline at end of file

plugins/nyan/nyan.plugin.zsh

-print -Pn '%F{yellow}'
-cat >&2 <<-EOD
-	nyan plugin:
-	The nyancat server used by this plugin was shut down due to increased
-	bandwidth costs, so the nyan plugin no longer works. You can get the
-	same functionality in some distributions by installing the nyancat package,
-	or you can compile it yourself.
-	See https://github.com/klange/nyancat for more information.
-EOD
-print -Pn '%f'