[swift4] update Alamofire from 4.7.0 to 4.9.0

[4brunu]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\. If contributing template-only or documentation-only changes which will change sample output, be sure to build the project first.
• Filed the PR against the correct branch: master, 4.1.x, 5.0.x. Default: master.
• Copied the technical committee to review the pull request if your PR is targeting a particular programming language.

Description of the PR

According to the last checkbox I think I should tag you, sorry if I'm wrong, first contribution...
@jgavris @ehyche @Edubits @jaz-ah @d-date

This PR fixes #2300 by updating the version of alomofire in podspec and cartfile.

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[wing328]

@4brunu thanks for the PR. The CI failure is not related to this PR.

[wing328]

Tested locally and the tests passed:

DateFormatTests
    ✓ testCodableAlwaysResultsInUTCEncodedDate (0.079 seconds)
    ✓ testEncodeToJSONAlwaysResultsInUTCEncodedDate (0.001 seconds)
PetAPITests
    ✓ test1CreatePet (0.673 seconds)
    ✓ test2GetPet (0.391 seconds)
    ✓ test3DeletePet (0.318 seconds)
StoreAPITests
    ✓ test1PlaceOrder (0.336 seconds)
    ✓ test2GetOrder (0.353 seconds)
    ✓ test3DeleteOrder (0.338 seconds)
    ✓ testDownloadProgress (0.699 seconds)
UserAPITests
    ✓ testLogin (0.835 seconds)
    ✓ testLogout (0.333 seconds)
    ✓ testPathParamsAreEscaped (0.000 seconds)


Executed 12 tests, with 0 failures (0 unexpected) in 4.357 (4.362) seconds
2019-10-01 15:53:40.523 xcodebuild[8807:1726130] [MT] IDETestOperationsObserverDebug: 397.368 elapsed -- Testing started completed.
2019-10-01 15:53:40.523 xcodebuild[8807:1726130] [MT] IDETestOperationsObserverDebug: 0.000 sec, +0.000 sec -- start
2019-10-01 15:53:40.523 xcodebuild[8807:1726130] [MT] IDETestOperationsObserverDebug: 397.368 sec, +397.368 sec -- end
▸ Test execute Succeeded
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS

[wing328]

I'll run swiftlint in another PR to reformat the code.

[wing328]

@4brunu thanks for the PR. Given that my local test result is good, let's go with what you've changed so far.

[wing328]

@4brunu if you plan to submit more PRs for Swift, please install swiftlint locally in your machine.

ref: https://github.com/realm/SwiftLint

[4brunu]

@wing328 thanks 👍