Pull Request Checklist

• Have you added new tests to prevent regressions? Not applicable. This changes a workflow step only.
• Does npm run test or npm run test-DIALECT pass with this change (including linting)? CI on this pull request is the test.
• Is a documentation update included? Not applicable.
• Did you update the typescript typings accordingly? Not applicable.
• Does the description below contain a link to an existing issue? Closes v6 CI: postgres-native legs on Node 10 fail because pg-native is installed unpinned #18312.
• Did you follow the commit message conventions explained in CONTRIBUTING.md? Yes.

Description Of Change

Closes #18312.

The workflow installs pg-native unpinned, after the lockfile install, so CI always takes
the newest release:

- run: yarn install --frozen-lockfile --ignore-engines
- run: yarn add pg-native --ignore-engines
  if: matrix.native

pg-native 3.8.0 added nullish coalescing, which Node 10 cannot parse, so the module throws
at load time before mocha runs a single test. That takes out four legs of the test-postgres
matrix on every pull request against v6:

node_modules/pg-native/index.js:153
  return statusMap[this.pq.transactionStatus()] ?? null
                                               ^
SyntaxError: Unexpected token ?

This pins the version. The Node 10 legs are the reason a pin is needed, and I pinned all
native legs rather than only the Node 10 ones, so the matrix stays uniform and no leg
depends on whatever npm publishes next.

Verification

Under node:10-alpine, Node v10.24.1, node --check on every .js file in each package:

pg-native pins pg-types to an exact version, and libpq above is the resolved
transitive, so 3.7.0 is enough on its own. The native build itself was never the problem:
the Node 10 legs today get through install and fail at test time.

I could not run the native suite locally, because libpq needs headers this machine does not
have. CI on this pull request covers that.

Alternative I did not take

Adding pg-native to devDependencies would let --frozen-lockfile govern it and end this
class of failure for good. I left it alone, because every leg and every contributor would
then build libpq from source, and only the four native legs need it.