fix(gnovm): make static-analysis handle block stmt (#3313)

as the title says.

it give incorrect error before fix:
```
unexpected panic: main/files/block0.gno:3:1: [function "foo" does not terminate]
```

gnovm/pkg/gnolang/static_analysis.go

@@ -108,6 +108,8 @@ func (s *staticAnalysis) staticAnalysisExpr(expr Expr) bool {
 // indicating whether a statement is terminating or not
 func (s *staticAnalysis) staticAnalysisStmt(stmt Stmt) bool {
 	switch n := stmt.(type) {
+	case *BlockStmt:
+		return s.staticAnalysisBlockStmt(n.Body)
 	case *BranchStmt:
 		switch n.Op {
 		case BREAK:

gnovm/tests/files/block0.gno

@@ -0,0 +1,14 @@
+package main
+
+func foo() int {
+	{
+		return 1
+	}
+}
+
+func main() {
+	println(foo())
+}
+
+// Output:
+// 1