Update Go to 1.16.3

go1.16.3 (released 2021/04/01) includes fixes to the compiler, linker, runtime,
the go command, and the testing and time packages. See the Go 1.16.3 milestone
on our issue tracker for details:

https://github.com/golang/go/issues?q=milestone%3AGo1.16.3+label%3ACherryPickApproved

full diff: https://github.com/golang/go/compare/go1.16.2...go1.16.3

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

.github/workflows/nightly.yml

@@ -18,7 +18,7 @@ jobs:
     steps:
       - uses: actions/setup-go@v2
         with:
-          go-version: '1.16.2'
+          go-version: '1.16.3'
 
       - uses: actions/checkout@v2
         with:
@@ -135,7 +135,7 @@ jobs:
     steps:
       - uses: actions/setup-go@v2
         with:
-          go-version: '1.16.2'
+          go-version: '1.16.3'
 
       - uses: actions/checkout@v2
         with: