fix: use unicode dot for tags separation

This makes the separator appear correctly on all platforms (in theory)

assets/style/article.css

@@ -50,7 +50,7 @@ article > p {
 }
 
 .article-tags > ul > li:not(:last-child)::after {
-  content: " ⦁";
+  content: " •";
 }
 
 .article-dates {
@@ -129,5 +129,5 @@ article > p {
 }
 
 .article-frontmatter-tags > ul > li:not(:last-child)::after {
-  content: " ⦁";
+  content: " •";
 }

assets/style/tags.css

@@ -15,5 +15,5 @@
 }
 
 .tags > ul > li:not(:last-child)::after {
-  content: " ⦁";
+  content: " •";
 }