Align indentation where cabal check warns about it

[philderbeast]

Fixes the warning about inconsistent indentation in the package.

$ cabal check
...
Warning: elm.cabal:42:5: Inconsistent indentation. Indentation jumps at lines
42
...

Found when adding elm-compiler as an Updo example. I noticed the warning there:

$ cabal build all --enable-tests --enable-benchmarks
Warning: Unknown/unsupported 'ghc' version detected (Cabal 3.11.0.0 supports
'ghc' version < 9.8): /home/philderbeast/.ghcup/bin/ghc is version 9.8.1
Resolving dependencies...
Build profile: -w ghc-9.8.1 -O1
In order, the following will be built (use -v for more details):
 - elm-0.19.1 (exe:elm) (first run)
Warning: elm.cabal:42:5: Inconsistent indentation. Indentation jumps at lines
42
Configuring executable 'elm' for elm-0.19.1...
...

[github-actions[bot]]

Thanks for suggesting these code changes. To set expectations:

• Pull requests are reviewed in batches, so it can take some time to get a response.
• Smaller pull requests are easier to review. To fix nine typos, nine specific issues will always go faster than one big one. Learn why here.
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