Matrix tests can't find vector package

[phtb233]

The tests for the matrix exercise pass locally but fail when using exercism submit or the online editor with this error message:

Cabal file info not found for vector-0.12.1.2@sha256:9291bc581f36e51d5bda9fce57cb980fbec3dd292996896f285fef39eb80a9a0,7364, updating
Selected mirror https://hackage.haskell.org/
Downloading root
HttpExceptionRequest Request {
  host                 = "hackage.haskell.org"
  port                 = 443
  secure               = True
  requestHeaders       = [("Accept-Encoding",""),("User-Agent","Haskell pantry package")]
  path                 = "/root.json"
  queryString          = ""
  method               = "GET"
  proxy                = Nothing
  rawBody              = False
  redirectCount        = 10
  responseTimeout      = ResponseTimeoutDefault
  requestVersion       = HTTP/1.1
}
 (ConnectionFailure Network.Socket.getAddrInfo (called with preferred socket type/protocol: AddrInfo {addrFlags = [AI_ADDRCONFIG], addrFamily = AF_UNSPEC, addrSocketType = Stream, addrProtocol = 0, addrAddress = <assumed to be undefined>, addrCanonName = <assumed to be undefined>}, host name: Just "hackage.haskell.org", service name: Just "443"): does not exist (Try again))

Community submissions from more than 2 months ago were successful, but recent submissions also fail.

[ErikSchierboom]

See exercism/haskell#1006

[ErikSchierboom]

Fixed by #32