Fix some linter errors

[alumi]

This PR fixes coding styles of test codes and does not introduce any changes of its behavior.

clj-kondo reports test/cljam/io/gff_test.clj:319:70: error: Unresolved symbol: ?str on the master branch.
I've removed the type hints in 909e6d2 because adding type hints to the symbols in expr of clojure.test/are has no effects on suppressing reflections.
In f13581a, I've also fixed some coding styles warned by kibit.

Details

The strange behavior of the :unresolved-symbol error is due to differences in how metadata is handled.
clojure.test/are uses clojure.template/do-template which replaces symbols using clojure.walk/postwalk-replace.
Since a symbol’s metadata does not affect its identity during replacement, this process works as expected.
However, clj-kondo emulates clojure.template/do-template with clojure.walk/postwalk-replace, but it operates on AST nodes, which have :meta fields directly attached.
This difference causes replacement failure.
As seen above, since clojure.test/are replaces symbols in its expr, we need type information on args rather than on the symbols in expr.

user> (set! *warn-on-reflection* true)
user> (def s "A")
user> (are [x] (.length ^String x) s)
Reflection warning, *cider-repl chrovis/cljam:localhost:64423(clj)*:79:16 - reference to field length can't be resolved.
1
user> (are [x] (.length x) ^String s)
1

In the case of this PR, adding type hints is unnecessary because args are already typed vars.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.00%. Comparing base (9408e13) to head (f13581a).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #338      +/-   ##
==========================================
+ Coverage   89.96%   90.00%   +0.04%     
==========================================
  Files         104      104              
  Lines        9723     9723              
  Branches      529      529              
==========================================
+ Hits         8747     8751       +4     
+ Misses        447      445       -2     
+ Partials      529      527       -2     

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[niyarin]

Thank you for the fix.
I confirmed that the issue with the linter warning in test/cljam/io/gff_test.clj has been resolved.

[alumi]

@niyarin Thank you for reviewing! 🙏