Remove unused EOF constants

These were left over from when we still had a iterator type dedicated to
iterating over bytes, without the need for allocating Option values.

Changelog: other

std/src/std/iter.inko

@@ -23,9 +23,6 @@
 import std.cmp.Equal
 import std.option.Option
 
-# The "byte" that signals the end in a `Bytes` iterator.
-let pub EOF = -1
-
 # A generic iterator over a sequence of values of type `T`.
 trait pub Iter[T] {
   # Returns the next value in the iterator.

std/src/std/json.inko

@@ -65,7 +65,6 @@ import std.iter.Peekable
 import std.string.(Bytes, StringBuffer, ToString)
 import std.utf8
 
-let EOF = -1
 let BRACKET_OPEN = 0x5B
 let BRACKET_CLOSE = 0x5D
 let CURLY_OPEN = 0x7B

std/test/std/test_byte_array.inko

@@ -1,6 +1,5 @@
 import helpers.(hash)
 import std.fmt.(fmt)
-import std.iter.EOF
 import std.test.Tests
 
 fn pub tests(t: mut Tests) {

std/test/std/test_string.inko

@@ -1,7 +1,6 @@
 import helpers.(hash)
 import std.fmt.(fmt)
 import std.fs.path.Path
-import std.iter.EOF
 import std.test.Tests
 
 fn pub tests(t: mut Tests) {