Temporary disable test for dropping vtable

bump codecov/codecov-action@v2 (mattn#957)

Update amalgamation code (mattn#955)

* Update amalgamation code

* Apply realPy's patch

Update amalgamation code

Update amalgamation code (mattn#896)

Support vfs for Open (mattn#877)

Closes mattn#876

Fix mattn#860 extenstion entry bug (mattn#861)

Fix overshadowing of entrypoint variable.

Add build tag ignore for upgrade script (mattn#851)

Fix "cannot start a transaction within a transaction" issue (mattn#764)…

… (mattn#765)

* Fix "cannot start a transaction within a transaction" issue

[why]
If db.BeginTx(ctx, nil) context is cancelled too fast, "BEGIN" statement can be
completed inside DB, but we still try to cancel it with sqlite3_interrupt.
In such case we get context.Cancelled or context.DeadlineExceeded from exec(),
but operation really completed. Connection returned into pool, and returns "cannot
start a transaction within a transaction" error for next db.BeginTx() call.

[how]
Handle status code returned from cancelled operation.

[testing]
Added unit-test which reproduces issue.

* Reduce TestQueryRowContextCancelParallel concurrency

[why]
Tests times out in travis-ci when run with -race option.

Update amalgamation code (mattn#842)

* Update amalgamation code

* Drop go1.9 and go1.10