CI failure on TestEngineFetch

[callahad]

Our CI workflow has started failing at:

--- FAIL: TestEngineFetch (0.27s)
panic: interface conversion: interface {} is *request.CoordinatedResponse, not []uint8 [recovered]
	panic: interface conversion: interface {} is *request.CoordinatedResponse, not []uint8

goroutine 31 [running]:
testing.tRunner.func1.2({0x13c9ce0, 0xc0012d0060})
	/opt/hostedtoolcache/go/1.20.2/x64/src/testing/testing.go:1526 +0x24e
testing.tRunner.func1()
	/opt/hostedtoolcache/go/1.20.2/x64/src/testing/testing.go:1529 +0x39f
panic({0x13c9ce0, 0xc0012d0060})
	/opt/hostedtoolcache/go/1.20.2/x64/src/runtime/panic.go:884 +0x213
github.com/suborbital/e2core/sat/engine2/enginetest.TestEngineFetch(0xc000170680)
	/home/runner/work/e2core/e2core/sat/engine2/enginetest/engine_test.go:159 +0x758
testing.tRunner(0xc000170680, 0x1450e80)
	/opt/hostedtoolcache/go/1.20.2/x64/src/testing/testing.go:[157](https://github.com/suborbital/e2core/actions/runs/4619606359/jobs/8168575352?pr=413#step:7:158)6 +0x10b
created by testing.(*T).Run
	/opt/hostedtoolcache/go/1.20.2/x64/src/testing/testing.go:[162](https://github.com/suborbital/e2core/actions/runs/4619606359/jobs/8168575352?pr=413#step:7:163)9 +0x3ea
FAIL	github.com/suborbital/e2core/sat/engine2/enginetest	0.484s

Looking at the Actions dashboard, this is a recent failure:

This workflow successfully ran as part of PR #411 on April 1st, and we've not merged anything since then, so something external has changed to cause this failure.

[javorszky]

So that one is... basically it fetches the 1password error page, and fails and returns whatever was fetched.

The moment 1password changes the html of their error page, this will start failing.

See https://github.com/suborbital/e2core/blob/main/sat/engine2/enginetest/engine_test.go#L158-L160