chore(ci): update tm2 timeout on CI (gnolang#1337)

It should prevent certain flaky tests from failing on GH.
In any case, it increases the high-level timeout to be greater than the
timeout for running 'go test'.

Related to issue gnolang#1320.

.github/workflows/tm2.yml

@@ -55,7 +55,7 @@ jobs:
  - _test.pkg.bft
  - _test.pkg.others
  runs-on: ubuntu-latest
- timeout-minutes: 15
+ timeout-minutes: 21
  steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-go@v4
@@ -65,7 +65,7 @@ jobs:
  working-directory: tm2
  run: |
  export GOPATH=$HOME/go
- export GOTEST_FLAGS="-v -p 1 -timeout=30m -coverprofile=coverage.out -covermode=atomic"
+ export GOTEST_FLAGS="-v -p 1 -timeout=20m -coverprofile=coverage.out -covermode=atomic"
  make ${{ matrix.args }}
  touch coverage.out
  - uses: actions/upload-artifact@v3