Revert category change to HiGHS release

This changed existing links.

x-ref #118

Author: odow

_posts/2021-02-11-highs.md

@@ -2,7 +2,7 @@
 layout: post
 title:  "HiGHS.jl 0.1 released"
 date:   2021-02-11
-categories: [releases]
+categories: [solvers]
 ---
 
 We are happy to announce the initial `v0.1` release of [HiGHS.jl](https://github.com/jump-dev/HiGHS.jl),