Update CI xcode to 10.1

Author: tsolomko

.travis.yml

@@ -3,7 +3,7 @@ jobs:
     - stage: test
       language: swift
       os: osx
-      osx_image: xcode10
+      osx_image: xcode10.1
       script:
       - swift build
       - swift test --filter BitByteDataTests
@@ -21,7 +21,7 @@ jobs:
       if: NOT (tag IS present)
       language: swift
       os: osx
-      osx_image: xcode10
+      osx_image: xcode10.1
       script:
       # On macOS swift test (i.e. XCTest) outputs to stderr so we need to redirect pipes.
       - swift test -c release --filter BitByteDataBenchmarks 2>&1 | ./ppbenchmarks.py 
@@ -39,7 +39,7 @@ jobs:
       if: tag IS present
       language: generic
       os: osx
-      osx_image: xcode10
+      osx_image: xcode10.1
       env:
         secure: 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
       before_install: