ci(pr-build): give go test a 20m package timeout (#1735)

## Description

The Build Binaries job in `pr-build.yml` runs `go test ./...` with Go's
default 10-minute per-package timeout. `internal/server` now takes close
to that on a loaded runner, so the job failed on PR #1718 (run
39776808883) with `panic: test timed out after 10m0s` while every test
was passing; the test running at that moment had been going for 10
seconds. The same job passed on the previous head of that PR and on the
run in between, so this is a budget, not a hang.

Set `-timeout 20m` on both `go test` lines, matching what
`unit-tests.yml` already uses. CI-only change.

Author: Dumbris

.github/workflows/pr-build.yml

@@ -219,9 +219,9 @@ jobs:
         run: |
           # On Windows, skip internal/server tests (E2E tests timeout after 11 minutes)
           if [ "${{ matrix.goos }}" = "windows" ]; then
-            go test -tags nogui -v -skip "E2E|Binary|MCPProtocol" $(go list ./... | grep -v 'internal/server$')
+            go test -tags nogui -v -timeout 20m -skip "E2E|Binary|MCPProtocol" $(go list ./... | grep -v 'internal/server$')
           else
-            go test -tags nogui -v -skip "E2E|Binary|MCPProtocol" ./...
+            go test -tags nogui -v -timeout 20m -skip "E2E|Binary|MCPProtocol" ./...
           fi
         env:
           TIKTOKEN_CACHE_DIR: ${{ runner.temp }}/tiktoken