Clear about page credits before populating them (#1840)

While working on #1835, I
noticed a bug in the "About" dialog where the list of credits keep
growing each time the dialog gets opened.

Demo of the issue:


https://github.com/user-attachments/assets/dd4cb4e9-9406-4d50-b42f-149684181d7b


This PR clears the credits before populating them.

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href="https://codeapprove.com/pr/tiny-pilot/tinypilot/1840"><img
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app/templates/custom-elements/about-dialog.html

@@ -117,6 +117,7 @@ <h3>About TinyPilot</h3>
             metadata.sort((a, b) => a.name.localeCompare(b.name, "en"));
 
             const creditsDiv = this.shadowRoot.querySelector(".credits");
+            creditsDiv.innerHTML = "";
             for (const project of metadata) {
               // Skip displaying TinyPilot in the list of dependencies, since we
               // display the TinyPilot license in a special way.