Expose SetJob to make EraseNeeds work (#35)

Related to #33

Reviewed-on: https://gitea.com/gitea/act/pulls/35
Reviewed-by: Lunny Xiao <[email protected]>

pkg/jobparser/testdata/erase_needs.in.yaml

@@ -0,0 +1,16 @@
+name: test
+jobs:
+  job1:
+    runs-on: linux
+    steps:
+      - run: uname -a
+  job2:
+    runs-on: linux
+    steps:
+      - run: uname -a
+    needs: job1
+  job3:
+    runs-on: linux
+    steps:
+      - run: uname -a
+    needs: [job1, job2]

pkg/jobparser/testdata/erase_needs.out.yaml

@@ -0,0 +1,23 @@
+name: test
+jobs:
+  job1:
+    name: job1
+    runs-on: linux
+    steps:
+      - run: uname -a
+---
+name: test
+jobs:
+  job2:
+    name: job2
+    runs-on: linux
+    steps:
+      - run: uname -a
+---
+name: test
+jobs:
+  job3:
+    name: job3
+    runs-on: linux
+    steps:
+      - run: uname -a