Setup BenchmarkCI (#737)

Author: tkf

.github/workflows/benchmark.yml

@@ -0,0 +1,21 @@
+name: Run benchmarks
+
+on:
+  pull_request:
+
+jobs:
+  Benchmark:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: julia-actions/setup-julia@latest
+        with:
+          version: 1.3
+      - name: Install dependencies
+        run: julia -e 'using Pkg; pkg"add PkgBenchmark BenchmarkCI@0.1"'
+      - name: Run benchmarks
+        run: julia -e 'using BenchmarkCI; BenchmarkCI.judge()'
+      - name: Post results
+        run: julia -e 'using BenchmarkCI; BenchmarkCI.postjudge()'
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -1,6 +1,8 @@
 *.jl.cov
 *.jl.*.cov
 *.jl.mem
+/.benchmarkci
 /Manifest.toml
+/benchmark/*.json
 /benchmark/Manifest.toml
 /docs/Manifest.toml