Update thesis/endian constraint to ^0.3 to fix PHP 8.5 deprecation warnings

[iGrog]

thesis/amqp currently requires "thesis/endian": "^0.1.0" in composer.json.

thesis/endian 0.1.0 uses chr() with values outside the 0–255 range, which triggers deprecation warnings on PHP 8.5:

  Deprecated: chr(): Providing a value not in-between 0 and 255 is deprecated,
  this is because a byte value must be in the [0, 255] interval.
  The value used will be constrained using % 256
    at vendor/thesis/endian/src/endian.php:91

This was fixed in thesis/endian 0.3.0 (switched to bcmath), but the ^0.1.0 constraint in thesis/amqp prevents Composer from pulling the newer version.

Could the constraint be bumped to ^0.3?