Use gradle/gradle-build-action to reduce cache usage

[twyatt]

gradle/gradle-build-action provides sane/automatic caching for Gradle runs, which should use significantly less cache than our previous (overly aggressive) cache configuration.

[codecov]

Codecov Report

Merging #314 (f96a2af) into main (1c1547e) will decrease coverage by 25.14%.
Report is 225 commits behind head on main.
The diff coverage is 47.50%.

@@              Coverage Diff              @@
##               main     #314       +/-   ##
=============================================
- Coverage     94.44%   69.30%   -25.14%     
=============================================
  Files            13        9        -4     
  Lines           126      101       -25     
  Branches          8        2        -6     
=============================================
- Hits            119       70       -49     
- Misses            6       31       +25     
+ Partials          1        0        -1     

Files	Coverage Δ
coroutines/src/commonMain/kotlin/flow/Combine.kt	0.00% <ø> (ø)
...tines/src/commonMain/kotlin/delay/DelayStrategy.kt	47.50% <47.50%> (ø)

... and 6 files with indirect coverage changes

[github-actions]

Test Results

  96 files    96 suites   4s ⏱️
833 tests 824 ✔️   9 💤 0 ❌
850 runs  836 ✔️ 14 💤 0 ❌

Results for commit f96a2af.