Checking for base contract address instead of vault token symbol to detect eth as base

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 90.90909% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 80.76%. Comparing base (aca14c4) to head (21ffba2).

Files	Patch %	Lines
...gent0/ethpy/hyperdrive/interface/read_interface.py	66.66%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1435 +/- ## ========================================== - Coverage 80.76% 80.76% -0.01% ========================================== Files 104 104 Lines 6448 6447 -1 ========================================== - Hits 5208 5207 -1 Misses 1240 1240 ``` | [Flag](https://app.codecov.io/gh/delvtech/agent0/pull/1435/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=delvtech) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/delvtech/agent0/pull/1435/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=delvtech) | `80.76% <90.90%> (-0.01%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=delvtech#carryforward-flags-in-the-pull-request-comment) to find out more.

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