Update mellium.im/sasl to v0.2.1
The XMPP library now performs its own Base64 encoding and decoding since
this is no longer part of the SASL library (it's XMPP specific and
shouldn't have been in the SASL library to begin with).
all: bump to new xmlstream and fix flushing
Revert "all: new session XML read/write API"
This reverts commit 5265955b9c79963ea0c1b9f392db0e56b6a242a8.
all: new session XML read/write API
xmpp: update mod file and add checksums
xmpp: update go.mod file format
all: add lock file to start testing vgo