Add peakrdl-cli optional dependency

pyproject.toml

@@ -16,7 +16,7 @@ authors = [
 ]
 description = "Compile SystemRDL into a SystemVerilog control/status register (CSR) block"
 readme = "README.md"
-license = {file = "LICENSE"}
+license = {text = "GPLv3"}
 keywords = [
     "SystemRDL", "PeakRDL", "CSR", "compiler", "tool", "registers", "generator",
     "Verilog", "SystemVerilog", "register abstraction layer",
@@ -41,6 +41,11 @@ classifiers = [
     "Topic :: Scientific/Engineering :: Electronic Design Automation (EDA)",
 ]
 
+[project.optional-dependencies]
+cli = [
+    "peakrdl-cli >= 1.2.3",
+]
+
 [project.urls]
 Source = "https://github.com/SystemRDL/PeakRDL-regblock"
 Tracker = "https://github.com/SystemRDL/PeakRDL-regblock/issues"