fix attempt to get length of field 'constraints' (a nil value)

With luarocks 3.12.x the constraints is now nested inside
dependencies.queries table

Author: tkan145

src/rover/dsl.lua

@@ -73,9 +73,10 @@ local function rockspec(name)
         spec = rockspec,
         modules = modules }, rockspec_mt)
 
+    local dependencies = rockspec.dependencies.queries
 
-    for i=1, #(rockspec.dependencies) do
-        local dep = rockspec.dependencies[i]
+    for i=1, #(dependencies) do
+        local dep = dependencies[i]
         local version = {}
 
         for c=1, #(dep.constraints) do

src/rover/lock.lua

@@ -188,7 +188,7 @@ local function expand_dependencies(dep, dependencies, no_cache)
         existing.groups = merge_groups(existing.groups, groups)
     end
 
-    local matched, missing, _ = deps.match_deps(rockspec.dependencies, rockspec.rocks_provided, nil, 'one')
+    local matched, missing, _ = deps.match_deps(rockspec.dependencies.queries, rockspec.rocks_provided, nil, 'one')
 
     for _, dep in pairs(matched) do
         local query = queries.new(dep.name, nil, dep.version, false, "src|rockspec")