[ci] CircleCI removed xcode:9.0.1 image

The replacement run newer versions of macOS (10.13.3), making this job
obsolete as it tests nothing the other jobs don’t test.

.circleci/config.yml

@@ -10,17 +10,6 @@ executors:
 
 jobs:
 
-  macos-10_12_6-aat-fonts:
-    macos:
-      xcode: "9.0.1"
-    steps:
-      - checkout
-      - run: HOMEBREW_NO_AUTO_UPDATE=1 brew install pkg-config freetype glib cairo python3 ninja
-      - run: pip3 install meson --upgrade
-      - run: meson build
-      - run: meson compile -Cbuild # or ninja -Cbuild
-      - run: meson test -Cbuild --print-errorlogs
-
   macos-10_13_6-aat-fonts:
     macos:
       xcode: "10.1.0"
@@ -170,7 +159,6 @@ workflows:
 
   build:
     jobs:
-      - macos-10_12_6-aat-fonts
       - macos-10_13_6-aat-fonts
       - macos-10_14_4-aat-fonts
       - macos-10_15_3-aat-fonts