chore(ci): remove .appveyor.yml file

.appveyor.yml

@@ -1,18 +0,0 @@
-environment:
-  RUST_BACKTRACE: 1
-  matrix:
-  - TARGET: x86_64-pc-windows-msvc
-  - TARGET: i686-pc-windows-msvc
-  - TARGET: x86_64-pc-windows-gnu
-  - TARGET: i686-pc-windows-gnu
-install:
-  - curl -sSf -o rustup-init.exe https://win.rustup.rs/
-  - rustup-init.exe -y --default-host %TARGET%
-  - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
-  
-  - rustc -vV
-  - cargo -vV
-build: false
-test_script:
-  - cargo build
-  - cargo test