eliminate all use of deprecated "new Buffer"

Author: williamstein

src/packages/frontend/account/ssh-keys/fingerprint.ts

@@ -11,7 +11,7 @@ import md5 from "md5";
 const colons = (s: string) => s.replace(/(.{2})(?=.)/g, "$1:");
 
 export function compute_fingerprint(pub: string): string {
-  const pubbuffer = new Buffer(pub, "base64");
+  const pubbuffer = Buffer.from(pub, "base64");
   const key = md5(pubbuffer);
   return colons(key);
 }

src/packages/frontend/jupyter/output-messages/ipywidget.tsx

@@ -89,7 +89,6 @@ export function IpyWidget({ id: cell_id, value, actions }: WidgetProps) {
             <Button
               type="link"
               onClick={() => {
-                console.log("hi", cell_id);
                 actions.run_cell(cell_id);
               }}
             >

src/packages/jupyter/kernel/kernel.ts

@@ -1011,7 +1011,7 @@ class JupyterKernel extends EventEmitter implements JupyterKernelInterface {
     const dbg = this.dbg("send_comm_message_to_kernel");
     dbg({ msg_id, comm_id, target_name, data, buffers64 });
     if (buffers64 != null && buffers64.length > 0) {
-      buffers = buffers64?.map((x) => new Buffer(base64ToBuffer(x))) ?? [];
+      buffers = buffers64?.map((x) => Buffer.from(base64ToBuffer(x))) ?? [];
       dbg(
         "buffers lengths = ",
         buffers.map((x) => x.byteLength),