Update OWNERS approvers and reviewers: pkg/credentialprovider

pkg/credentialprovider/OWNERS

@@ -1,3 +1,26 @@
-assignees:
-  - erictune
-  - liggitt
+approvers:
+- erictune
+- liggitt
+reviewers:
+- thockin
+- smarterclayton
+- deads2k
+- yujuhong
+- brendandburns
+- derekwaynecarr
+- vishh
+- mikedanese
+- davidopp
+- pmorie
+- dchen1107
+- justinsb
+- eparis
+- dims
+- krousey
+- resouer
+- mbohlool
+- david-mcmahon
+- mfojtik
+- therc
+- lixiaobing10051267
+- goltermann

pkg/credentialprovider/aws/OWNERS

@@ -0,0 +1,6 @@
+reviewers:
+- justinsb
+- david-mcmahon
+- therc
+- lixiaobing10051267
+- goltermann

pkg/credentialprovider/gcp/OWNERS

@@ -0,0 +1,12 @@
+reviewers:
+- thockin
+- deads2k
+- yujuhong
+- derekwaynecarr
+- vishh
+- mikedanese
+- davidopp
+- eparis
+- dims
+- david-mcmahon
+- therc