build: Use go 1.14.7

From the go release notes:

go1.14.3 (released 2020/05/14) includes fixes to cgo, the compiler, the
runtime, and the go/doc and math/big packages.

go1.14.4 (released 2020/06/01) includes fixes to the go doc command, the
runtime, and the encoding/json and os packages.

go1.14.5 (released 2020/07/14) includes security fixes to the
crypto/x509 and net/http packages.

go1.14.6 (released 2020/07/16) includes fixes to the go command, the
compiler, the linker, vet, and the database/sql, encoding/json,
net/http, reflect, and testing packages.

go1.14.7 (released 2020/08/06) includes security fixes to the
encoding/binary package.

https://golang.org/doc/devel/release.html#go1.14.minor

.go-version

@@ -1 +1 @@
-1.14.2
+1.14.7