go.mod: Specify that we use the Go 1.17 language in this module

The main motivation here is that we were apparently using bit shifting
with signed shift amounts even though modern Go toolchains seem to raise
that as an error if the go.mod file selects a language version less than
Go 1.13.

Go 1.17 is therefore newer than we strictly need to solve that particular
problem, but gets us caught up with a relatively release of the language.
This alone doesn't break compatibility for anyone using older versions of
Go with HCL, since the Go toolchain will still attempt to compile modules
targeting later versions and will only mention the newer language version
if compilation would already have failed for some other reason.

go.mod

@@ -1,6 +1,6 @@
 module github.com/hashicorp/hcl/v2
 
-go 1.12
+go 1.17
 
 require (
 	github.com/agext/levenshtein v1.2.1
@@ -12,11 +12,18 @@ require (
 	github.com/kr/pretty v0.1.0
 	github.com/kylelemons/godebug v0.0.0-20170820004349-d65d576e9348
 	github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7
-	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/sergi/go-diff v1.0.0
 	github.com/spf13/pflag v1.0.2
-	github.com/stretchr/testify v1.2.2 // indirect
 	github.com/zclconf/go-cty v1.8.0
 	github.com/zclconf/go-cty-debug v0.0.0-20191215020915-b22d67c1ba0b
 	golang.org/x/crypto v0.0.0-20220517005047-85d78b3ac167
 )
+
+require (
+	github.com/kr/text v0.1.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.2.2 // indirect
+	golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1 // indirect
+	golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1 // indirect
+	golang.org/x/text v0.3.6 // indirect
+)

go.sum

@@ -41,8 +41,6 @@ github.com/zclconf/go-cty v1.8.0/go.mod h1:vVKLxnk3puL4qRAv72AO+W99LUD4da90g3uUA
 github.com/zclconf/go-cty-debug v0.0.0-20191215020915-b22d67c1ba0b h1:FosyBZYxY34Wul7O/MSKey3txpPYyCqVO5ZyceuQJEI=
 github.com/zclconf/go-cty-debug v0.0.0-20191215020915-b22d67c1ba0b/go.mod h1:ZRKQfBXbGkpdV6QMzT3rU1kSTAnfu1dO8dPKjYprgj8=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20220331220935-ae2d96664a29 h1:tkVvjkPTB7pnW3jnid7kNyAMPVWllTNOf/qKDze4p9o=
-golang.org/x/crypto v0.0.0-20220331220935-ae2d96664a29/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
 golang.org/x/crypto v0.0.0-20220517005047-85d78b3ac167 h1:O8uGbHCqlTp2P6QJSLmCojM4mN6UemYv8K+dCnmHmu0=
 golang.org/x/crypto v0.0.0-20220517005047-85d78b3ac167/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
 golang.org/x/net v0.0.0-20180811021610-c39426892332/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=