Release 3.6.0 (#239)

* chore: update dependencies

* chore: update user agent for measurements

* chore: we're now at v3.6.0

* chore: update assets

* chore: update bundled CA

* fix: address some goreportcard.com warnings

* fix(debian/changelog): zap release that breaks out build scripts

We're forcing the content of changelog with `dch`, so it's fine to
not have any specific new release in there.

* fix: make sure tests are passing locally

Notably, I removed a chunk of code where we were checking for network
activity. Now we don't fetch the databases and it's not important. Before,
it was important because the databases are ~large.

* fix: temporarily comment out riseupvn integration tests

See https://github.com/ooni/probe/issues/1354 for work aimed at
reducing the rate of false positives (thanks @cyBerta!)

internal/engine/netx/gocertifi/certifi.go

@@ -1,5 +1,5 @@
 // Code generated by go generate; DO NOT EDIT.
-// 2021-01-29 09:54:51.941105652 +0100 CET m=+1.231498959
+// 2021-03-03 11:48:43.129132377 +0100 CET m=+2.301468593
 // https://curl.haxx.se/ca/cacert.pem
 
 package gocertifi
@@ -3241,7 +3241,7 @@ kpzNNIaRkPpkUZ3+/uul9XXeifdy
 `
 
 // CACerts builds an X.509 certificate pool containing the
-// certificate bundle from https://curl.haxx.se/ca/cacert.pem fetch on 2021-01-29 09:54:51.941105652 +0100 CET m=+1.231498959.
+// certificate bundle from https://curl.haxx.se/ca/cacert.pem fetch on 2021-03-03 11:48:43.129132377 +0100 CET m=+2.301468593.
 // Returns nil on error along with an appropriate error code.
 func CACerts() (*x509.CertPool, error) {
 	pool := x509.NewCertPool()