Fix #210: declare missing delete-button column in saved pastes table

/mine rows render 7 cells (ID + delete button) but the colgroup and
thead only declared 6 columns, so under table-layout:fixed the delete
button cell overlapped the ID column at narrower widths. Add a
col-del column + empty header th to match the row cells.

internal/web/templates/mine.html

@@ -8,7 +8,7 @@
   <div class="search"><input id="filter" placeholder="Search…"><span class="search-spinner" id="search-spinner"></span></div>
   <div class="float">
     <table>
-      <colgroup><col class="col-a"><col class="col-b"><col class="col-c"><col class="col-d2"><col class="col-e"><col class="col-f"></colgroup>
+      <colgroup><col class="col-a"><col class="col-b"><col class="col-c"><col class="col-d2"><col class="col-e"><col class="col-f"><col class="col-del"></colgroup>
       <thead><tr>
         <th data-sort="title" class="sortable"><span class="sort-ind"></span>Paste</th>
         <th data-sort="language" class="sortable"><span class="sort-ind"></span>Language</th>
@@ -16,6 +16,7 @@
         <th data-sort="created_at" class="sortable"><span class="sort-ind"></span>Created</th>
         <th data-sort="custom_slug" class="sortable"><span class="sort-ind"></span>URL</th>
         <th data-sort="id" class="sortable"><span class="sort-ind"></span>ID</th>
+        <th aria-label="Delete"></th>
       </tr></thead>
       <tbody id="rows"></tbody>
     </table>