chore: ignore direnv .envrc files (#3029)

For direnv users - ignore .envrc files that may be setting local custom
settings such as the desired feature flag set for testing.

Author: t0yv0

.gitignore

@@ -14,4 +14,6 @@ testing/coverage.txt
 pf/coverage.out
 pf/tests/coverage.out
 
-pulumi-hcl-lint
+pulumi-hcl-lint
+
+.envrc