bugfix(PageHeader): Use font-weight initial to match the styled component styling (#5852)

Author: jonrohan

.changeset/old-taxis-notice.md

@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+bugfix(PageHeader): Use font-weight initial to match the styled component styling 

packages/react/src/PageHeader/PageHeader.module.css

@@ -229,7 +229,7 @@
   display: flex;
   padding-top: var(--base-size-8);
   font-size: var(--text-body-size-medium, 0.875rem);
-  font-weight: var(--base-text-weight-light);
+  font-weight: var(--base-text-weight-normal);
   line-height: var(--text-body-lineHeight-medium, 1.4285);
   flex-direction: row;
   grid-row: var(--grid-row-order-description);