subscriber: dim Compact targets, matching the default formatter (tokio-rs#2409)

Fixes tokio-rs#2408

Just switch to use `dim`

Before:
![2022-12-08_13-58-40](https://user-images.githubusercontent.com/623453/206576169-63ee4e20-b56f-4c63-a9b3-80ba2e97eec9.png)
After:
![2022-12-08_13-55-36](https://user-images.githubusercontent.com/623453/206576055-878d360f-7b95-4e18-bc31-4fb6f1b71a3a.png)
Full mode for comparison:
![2022-12-08_13-55-48](https://user-images.githubusercontent.com/623453/206576054-6e38852c-cb3a-4b84-98e5-50463cdb5073.png)
; Conflicts:
;	tracing-subscriber/src/fmt/format/mod.rs

Author: davidbarsky

.github/workflows/CI.yml

@@ -229,20 +229,8 @@ jobs:
         - tracing-tower
         - tracing
         toolchain:
-        - 1.49.0
+        - 1.56.0
         - stable
-        # TODO(eliza): remove this when appender is on the same MSRV.
-        #              same for tracing subscriber
-        exclude:
-        - subcrate: tracing-appender
-          toolchain: 1.49.0
-        - subcrate: tracing-subscriber
-          toolchain: 1.49.0
-        include:
-        - subcrate: tracing-appender
-          toolchain: 1.53.0
-        - subcrate: tracing-subscriber
-          toolchain: 1.50.0
     steps:
     - uses: actions/checkout@v3
     - name: "install Rust ${{ env.APPENDER_MSRV }}"