switch to new sync/atomic helpers in go1.19 (#728)

These new helpers make the code a lot cleaner. I confirmed that the
simple helpers like `atomic.Int64` don't add any extra overhead as they
get inlined by the compiler. `atomic.Pointer` adds an extra method call
as it no longer gets inlined, but we aren't using these on the hot path
so it is probably okay.

.github/workflows/release.yml

@@ -10,10 +10,10 @@ jobs:
     name: Build Linux All
     runs-on: ubuntu-latest
     steps:
-      - name: Set up Go 1.18
+      - name: Set up Go 1.19
         uses: actions/setup-go@v2
         with:
-          go-version: 1.18
+          go-version: 1.19
 
       - name: Checkout code
         uses: actions/checkout@v2
@@ -34,10 +34,10 @@ jobs:
     name: Build Windows
     runs-on: windows-latest
     steps:
-      - name: Set up Go 1.18
+      - name: Set up Go 1.19
         uses: actions/setup-go@v2
         with:
-          go-version: 1.18
+          go-version: 1.19
 
       - name: Checkout code
         uses: actions/checkout@v2
@@ -68,10 +68,10 @@ jobs:
       HAS_SIGNING_CREDS: ${{ secrets.AC_USERNAME != '' }}
     runs-on: macos-11
     steps:
-      - name: Set up Go 1.18
+      - name: Set up Go 1.19
         uses: actions/setup-go@v2
         with:
-          go-version: 1.18
+          go-version: 1.19
 
       - name: Checkout code
         uses: actions/checkout@v2