An in-memory only keyring has been added. This will be useful for us because
we have command line tools that we want to store longer term state in
something like the OSX keychain, but later we may wish to automate the utility
in a more transient, ephemeral way. In that case, the memory store will store
the data for the duration of the run and recreate them on subsequent runs.

I've additionally refactored slightly and added in a test for an Item.Equals
function.

remove debug code

tidy up

remove un-necessary condition

add unit test

Add Linux kernel keyring (keyctl) backend implementation

Add in memory keyring.

dashes in secret service backend break roundtrip (fix #82)

fix(kwallet): empty wallet key query

Revert "Add in memory keyring."

This updates the go modules (go.mod) to directly use the forked 99designs/go-keychain repository,
instead of requiring keybase/go-keychain and then using the replace directive.  The reasoning for
this is because the replace directive does not propagate to projects which depend on the go-keychain
project.  This means other projects which depend on the go-keychain project still need to add their
own replace directive.  Removing the replace directive from this project means that consumers
will automatically get the 99designs/go-keychain indirect dependency.  If there is a conflict
with another indirect dependency on keybase/go-keychain then that project can decide whether
to replace one or the other dependency.

Upgrade golang.org/x/sys to fix build on Windows ARM64

go.mod: use forked go-keychain

This fixes a CI test failure which is caused by using testing TempDir() function
which was added in go 1.15.

update go version used in CI

Expand pass dir path

pass backend: use PASSWORD_STORE_DIR if set

Fix tilde handling

Add golangci-lint and fix linting issues