Remove unused mypy ignore

[Fokko]

resolves #883 docs dbt-labs/docs.getdbt.com/#

check yaml...............................................................Passed
check json...........................................(no files to check)Skipped
fix end of files.........................................................Passed
trim trailing whitespace.................................................Passed
check for case conflicts.................................................Passed
black....................................................................Passed
flake8...................................................................Passed
mypy.....................................................................Failed
- hook id: mypy
- exit code: 1

dbt/adapters/spark/column.py:12: error: Unused "type: ignore" comment  [unused-ignore]
Found 1 error in 1 file (checked 8 source files)

Problem

Solution

Checklist

• [x] I have read the contributing guide and understand what's expected of me
• [x] I have run this code in development and it appears to resolve the stated issue
• [x] This PR includes tests, or tests are not required/relevant for this PR
• [x] This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX

[dataders]

looks like this change was already done in #880

[Fokko]

Looks like it, thanks @dataders