[integration] set expiry always to high value

Reasoning: a purchase is now completed when
the first proof comes in, so the test will no
longer wait until the request has expired.

tests/testIntegration.nim

@@ -88,11 +88,7 @@ ethersuite "Integration tests":
       client.post(baseurl1 & "/upload", "some file contents").body
 
     proc buy(cid: string): string =
-      when defined(windows):
-        # Windows builds in GitHub Actions need a longer expiry
-        let expiry = ((waitFor provider.currentTime()) + 30).toHex
-      else:
-        let expiry = ((waitFor provider.currentTime()) + 10).toHex
+      let expiry = ((waitFor provider.currentTime()) + 30).toHex
       let json = %*{"duration": "0x100", "maxPrice": "0x400", "expiry": expiry}
       client.post(baseurl1 & "/storage/request/" & cid, $json).body