Add GPU path, fast path, parallelism and 1.6

Author: ToucheSir

.buildkite/pipeline.yml

@@ -19,7 +19,9 @@ steps:
             Pkg.rm("ReTestItems") # not compatible with 1.6
           end'
     env:
-      GROUP: "CUDA" # TODO there are zero tests under this group
+      GROUP: "All"
+      TEST_FAST: true
+      TEST_WORKERS: 4
     if: build.message !~ /\[skip tests\]/
     timeout_in_minutes: 180
     matrix:

.github/workflows/CI.yml

@@ -26,11 +26,13 @@ jobs:
     runs-on: ${{ matrix.os }}
     env:
       GROUP: ${{ matrix.suite }}
+      TEST_FAST: ${{ matrix.version != '1' || matrix.os != 'ubuntu-latest' }}
     strategy:
       fail-fast: false
       matrix:
         version:
-          - '1' # Replace this with the minimum Julia version that your package supports.
+          - '1.6' # Replace this with the minimum Julia version that your package supports.
+          - '1'
           - 'nightly'
         os:
           - ubuntu-latest