website: Fix broken blog link

Change-Id: Id5897ce3112f34ca4360d9505de5eee42bd456ed
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/55163
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby Bruce <bbruce@ucdavis.edu>
diff --git a/_posts/2021-04-25-gem5-21-1-roadmap.md b/_posts/2021-04-25-gem5-21-1-roadmap.md
index e8eb824..cafb12f 100644
--- a/_posts/2021-04-25-gem5-21-1-roadmap.md
+++ b/_posts/2021-04-25-gem5-21-1-roadmap.md
@@ -41,7 +41,7 @@
 
 ### [Continue improving python-based stats](https://gem5.atlassian.net/browse/GEM5-644)
 
-In [gem5-21.0]({% post_url 2021-3-19-gem5-21-0 %}), we implemented a python-based API for accessing stats.
+In [gem5-21.0]({% post_url 2021-03-19-gem5-21-0 %}), we implemented a python-based API for accessing stats.
 However, this was not enabled by default.
 In 21.1, we are expecting this API to be improved and more features added.
 Let us know what you would like to see from a new stats interface in the [Jira issue](https://gem5.atlassian.net/browse/GEM5-644) or on the mailing list!