Add missing .lock files

stack-lts-18.yaml.lock

@@ -0,0 +1,12 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    sha256: 428ec8d5ce932190d3cbe266b9eb3c175cd81e984babf876b64019e2cbe4ea68
+    size: 590100
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/28.yaml
+  original: lts-18.28

stack-lts-19.yaml.lock

@@ -0,0 +1,12 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    sha256: 6d1532d40621957a25bad5195bfca7938e8a06d923c91bc52aa0f3c41181f2d4
+    size: 619204
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/19/33.yaml
+  original: lts-19.33

stack-lts-20.yaml.lock

@@ -0,0 +1,12 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    sha256: fc39d8afc97531d53d87b10abdef593bce503c0c1e46c2e9a84ebcbc78bf8470
+    size: 648432
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/20/2.yaml
+  original: lts-20.2