Use recorder instead of httptest.ResponseRecorder.

[k1LoW]

Simplify implementation.

[github-actions]

Code Metrics Report

	main (8148a60)	#78 (e215311)	+/-
Coverage	60.8%	61.2%	+0.4%
Code to Test Ratio	1:2.3	1:2.2	-0.1
Test Execution Time	43s	45s	+2s

Details

  |                     | main (8148a60) | #78 (e215311) |  +/-  |
  |---------------------|----------------|---------------|-------|
+ | Coverage            |          60.8% |         61.2% | +0.4% |
  |   Files             |              7 |             7 |     0 |
  |   Lines             |            441 |           446 |    +5 |
+ |   Covered           |            268 |           273 |    +5 |
- | Code to Test Ratio  |          1:2.3 |         1:2.2 |  -0.1 |
  |   Code              |            729 |           758 |   +29 |
  |   Test              |           1685 |          1685 |     0 |
- | Test Execution Time |            43s |           45s |   +2s |

Code coverage of files in pull request scope (75.0% → 76.2%)

Files	Coverage	+/-
rc.go	76.2%	+1.2%

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Reported by octocov

[pyama86]

It's so simple!!