chore: adds encoding for new models

Author: kuzminT

examples/How_to_count_tokens_with_tiktoken.ipynb

@@ -22,7 +22,7 @@
     "\n",
     "| Encoding name           | OpenAI models                                       |\n",
     "|-------------------------|-----------------------------------------------------|\n",
-    "| `o200k_base`            | `gpt-4o`, `gpt-4o-mini`                             |\n",
+    "| `o200k_base`            | `gpt-4o`, `gpt-4o-mini`, `gpt-4.1`, `gpt-4.1-mini`, `gpt-4.1-nano`, `gpt-4.5-preview`, `gpt-4.5`                             |\n",
     "| `cl100k_base`           | `gpt-4-turbo`, `gpt-4`, `gpt-3.5-turbo`, `text-embedding-ada-002`, `text-embedding-3-small`, `text-embedding-3-large`  |\n",
     "| `p50k_base`             | Codex models, `text-davinci-002`, `text-davinci-003`|\n",
     "| `r50k_base` (or `gpt2`) | GPT-3 models like `davinci`                         |\n",