test: disable failing err union switch tests on wasm

Author: dweiller

test/behavior/switch_on_captured_error.zig

@@ -7,6 +7,7 @@ const builtin = @import("builtin");
 
 test "switch on error union catch capture" {
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest;
 
     const S = struct {
         const Error = error{ A, B, C };
@@ -261,6 +262,7 @@ test "switch on error union catch capture" {
 
 test "switch on error union if else capture" {
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest;
 
     const S = struct {
         const Error = error{ A, B, C };