improve copy when no items found

there is no global state so its more appropriate say 'can't find'
rather than 'there aren't'

src/routes/r/[repo_naddr]/issues/+page.svelte

@@ -80,7 +80,7 @@
     </div>
     {#if !$issue_summaries.loading && filtered.length === 0}
       <div class="py-10 text-center lowercase">
-        there aren't any {statusKindtoText(status, 'issue')} issues
+        can't find any {statusKindtoText(status, 'issue')} issues
       </div>
     {:else}
       <ProposalsList

src/routes/r/[repo_naddr]/proposals/+page.svelte

@@ -84,7 +84,7 @@
     </div>
     {#if filtered.length === 0}
       <div class="py-10 text-center lowercase">
-        there aren't any {statusKindtoText(status, 'proposal')} proposals
+        can't find any {statusKindtoText(status, 'proposal')} proposals
       </div>
     {:else}
       <ProposalsList