fix: license check's false positive

Here is the license:
https://github.com/python-attrs/attrs/blob/24.3.0/LICENSE

However, the tool was reporting `UNKNOWN` license before authorizing it explicitly:
gathering licenses...
132 packages and dependencies.
check authorized packages...
131 packages.
check unknown packages...
1 package.
    attrs (24.3.0): UNKNOWN
      dependencies:
          attrs << aiohttp << open-autonomy
          attrs << aiohttp << web3 << open-aea-ledger-ethereum << open-aea-test-autonomy
          attrs << hypothesis
          attrs << jsonschema << cosmpy << open-aea-ledger-cosmos
          attrs << jsonschema << open-aea << open-aea-cli-ipfs << open-autonomy
          attrs << jsonschema << open-aea << open-aea-ledger-cosmos
          attrs << jsonschema << open-aea << open-aea-ledger-ethereum
          attrs << jsonschema << open-aea << open-aea-test-autonomy
          attrs << jsonschema << open-aea << open-autonomy
          attrs << jsonschema << open-autonomy
          attrs << jsonschema << openapi-schema-validator << openapi-core
          attrs << jsonschema << openapi-schema-validator << openapi-spec-validator << openapi-core
          attrs << jsonschema << openapi-spec-validator
          attrs << jsonschema << valory-docker-compose << open-autonomy
          attrs << jsonschema << web3
          attrs << pytest << open-aea-cli-ipfs
          attrs << pytest << open-aea-test-autonomy
          attrs << pytest << open-autonomy
          attrs << pytest << pytest-asyncio
          attrs << pytest << pytest-cov
          attrs << pytest << pytest-randomly
          attrs << pytest << pytest-rerunfailures

tox.ini

@@ -640,4 +640,6 @@ pathable: ==0.4.3
 pyinstaller: ==6.8.0
 pyinstaller-hooks-contrib: >=2024.6
 ; sub-dep of aiohttp, has PSF-2.0 License https://github.com/aio-libs/aiohappyeyeballs/blob/main/LICENSE
-aiohappyeyeballs: >=2.3.4,<3.0.0
+aiohappyeyeballs: >=2.3.4,<3.0.0
+; licence is MIT, but the tool does not detect it
+attrs: ==24.3.0