Fix grammar in isSerializableProps (#19072)

I believe this should read ["altogether"](https://www.merriam-webster.com/dictionary/altogether) not "all together".

packages/next/lib/is-serializable-props.ts

@@ -64,7 +64,7 @@ export function isSerializableProps(
         page,
         method,
         path,
-        '`undefined` cannot be serialized as JSON. Please use `null` or omit this value all together.'
+        '`undefined` cannot be serialized as JSON. Please use `null` or omit this value.'
       )
     }
 

test/unit/is-serializable-props.unit.test.js

@@ -101,7 +101,7 @@ Reason: \`function\` cannot be serialized as JSON. Please only return JSON seria
     expect(() => isSerializableProps('/', 'test', { toplevel: undefined }))
       .toThrowErrorMatchingInlineSnapshot(`
 "Error serializing \`.toplevel\` returned from \`test\` in \\"/\\".
-Reason: \`undefined\` cannot be serialized as JSON. Please use \`null\` or omit this value all together."
+Reason: \`undefined\` cannot be serialized as JSON. Please use \`null\` or omit this value."
 `)
 
     expect(() =>
@@ -136,7 +136,7 @@ Reason: \`function\` cannot be serialized as JSON. Please only return JSON seria
     expect(() => isSerializableProps('/', 'test', { k: { a: [1, undefined] } }))
       .toThrowErrorMatchingInlineSnapshot(`
 "Error serializing \`.k.a[1]\` returned from \`test\` in \\"/\\".
-Reason: \`undefined\` cannot be serialized as JSON. Please use \`null\` or omit this value all together."
+Reason: \`undefined\` cannot be serialized as JSON. Please use \`null\` or omit this value."
 `)
 
     expect(() =>