[saiyam-jain-dev]

Describe your change

Fixes #15635

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

Adler-32 is defined over a sequence of bytes. hashes/adler32.py previously iterated over Unicode characters (ord(plain_chr)), which matched the reference Adler-32 specification (zlib.adler32) only for pure-ASCII text. Non-ASCII input (e.g. '€100', '日本語テスト') and raw byte payloads produced checksums that diverged from standard implementations.

This PR:

• Supports both str and bytes / bytearray payloads.
• Encodes strings to UTF-8 bytes before calculating the checksum so that outputs match zlib.adler32 for all character sets.
• Adds comprehensive doctests covering ASCII strings, multibyte Unicode characters, byte sequences, empty inputs, and type verification.

Checklist

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues, then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".