Remove go 1.19 support, bump minimum to go 1.20 and add testing for 1.21

[mx-psi]

Fixes #8207

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (c46704a) 90.27% compared to head (150b4f4) 90.27%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8208   +/-   ##
=======================================
  Coverage   90.27%   90.27%           
=======================================
  Files         301      301           
  Lines       15581    15581           
=======================================
  Hits        14065    14065           
  Misses       1227     1227           
  Partials      289      289           

Files Changed	Coverage Δ
cmd/builder/internal/builder/main.go	60.82% <100.00%> (ø)

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[mx-psi]

There is a builder test consistently failing on this PR that is not failing on main

--- FAIL: TestSkipGenerate (1.75s)
    testing.go:1206: TempDir RemoveAll cleanup: remove C:\Users\RUNNER~1\AppData\Local\Temp\TestSkipGenerate2118395261\001: The process cannot access the file because it is being used by another process.
FAIL
FAIL	go.opentelemetry.io/collector/cmd/builder/internal/builder	1.836s
FAIL

[mx-psi]

I think the error is related to actions/runner-images/issues/712, although I am not sure why this only happens with Go 1.20.

[mx-psi]

I decided to skip the test and just list it on #5403 together with the other test that is already failing because of the same reason

[djaglowski]

LGTM.

To handle the required 1.19 check, I assume we remove the check, merge, and then add 1.21 check.

[bryan-aguilar]

Should this also use the ~ convention to force min version? Aligning across actions could make search and replace easier in the future.

[mx-psi]

Happy to do that, but I am worried that ~ is not a supported character on cache keys and since we use this variable here

opentelemetry-collector/.github/workflows/build-and-test.yml

Line 158 in 929cce9

key: unittest-${{ runner.os }}-go-build-${{ matrix.go-version }}-${{ hashFiles('**/go.sum') }}

it would break things, so I would prefer to work on this on a separate PR.

[dmitryax]

Apparently, I cannot update the protected branch rules. Submitted open-telemetry/community#1636

[mx-psi]

This is blocked by #8218

[arminru]

Apparently, I cannot update the protected branch rules. Submitted open-telemetry/community#1636

Branch rule updated: