feat: add comprehensive benchmark scripts for tokenizers

Add benchmark suites for cl100k_base, Llama 3, and o200k_base tokenizers.
Each script compares splintr performance against reference implementations
(tiktoken, HuggingFace) across single/batch encoding and decoding operations.

- benchmark_cl100k.py: GPT-4/GPT-3.5-turbo tokenizer benchmarks
- benchmark_llama3.py: Llama 3 family tokenizer benchmarks
- benchmark_o200k.py: GPT-4o tokenizer benchmarks

Benchmarks measure throughput (MB/s, tokens/s) and latency across various
text types (short, medium, long, code, multilingual) with visualization
support via matplotlib charts.

Author: farhan-syah

python/splintr/__init__.py

@@ -92,4 +92,4 @@
     "O200K_AGENT_TOKENS",
     "LLAMA3_AGENT_TOKENS",
 ]
-__version__ = "0.4.0"
+__version__ = "0.5.0"