[Codegen] Update LLVM version requirement for insertDeclare (apache#18123)

This PR fixes the codegen llvm version requirement. Prior to this PR,
we use `dbg_info_->di_builder_->insertDeclare` when LLVM version is
at least 19.0, while the new `insertDeclare` interface starts with
LLVM 20:
* 19.1.0: https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/include/llvm/IR/DIBuilder.h#L95-L98
* 20.1.0: https://github.com/llvm/llvm-project/blob/llvmorg-20.1.0/llvm/include/llvm/IR/DIBuilder.h#L950-L952

As a result, we may run into the following compilation error if
the LLVM version happens to be 19:

```
/home/ruihangl/Workspace/tvm/src/target/llvm/codegen_llvm.cc:2251:42: error: no matching function for call to 'llvm::DIBuilder::insertDeclare(llvm::AllocaInst*&, llvm::DILocalVariable*&, llvm::DIExpression*, llvm::DebugLoc, llvm::BasicBlock::iterator)'
 2251 |     dbg_info_->di_builder_->insertDeclare(
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
 2252 |         paramAlloca, param, dbg_info_->di_builder_->createExpression(), llvm::DebugLoc(di_loc),
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 2253 |         llvm::BasicBlock::iterator(store));
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/home/ruihangl/Workspace/tvm/src/target/llvm/codegen_llvm.cc:2293:42: error: no matching function for call to 'llvm::DIBuilder::insertDeclare(llvm::Value*&, llvm::DILocalVariable*&, llvm::DIExpression*, llvm::DebugLoc, llvm::BasicBlock::iterator)'
 2293 |     dbg_info_->di_builder_->insertDeclare(
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
 2294 |         llvm_value, local_var, dbg_info_->di_builder_->createExpression(), llvm::DebugLoc(di_loc),
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 2295 |         llvm::BasicBlock::iterator(insert_before));
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

To fixed this, we update the version requirement to LLVM 20.

Author: MasterJH5574

src/target/llvm/codegen_llvm.cc

@@ -2247,7 +2247,7 @@ void CodeGenLLVM::AddDebugInformation(llvm::Function* f_llvm, const Array<Type>&
 
     auto* store = builder.CreateStore(iter_param, paramAlloca);
     auto* di_loc = llvm::DILocation::get(*ctx, 0, 0, di_subprogram_);
-#if TVM_LLVM_VERSION >= 190
+#if TVM_LLVM_VERSION >= 200
     dbg_info_->di_builder_->insertDeclare(
         paramAlloca, param, dbg_info_->di_builder_->createExpression(), llvm::DebugLoc(di_loc),
         llvm::BasicBlock::iterator(store));
@@ -2289,7 +2289,7 @@ void CodeGenLLVM::AddDebugInformation(llvm::Value* llvm_value, const Var& tir_va
   auto* di_loc = llvm::DILocation::get(*llvm_target_->GetContext(), 0, 0, di_subprogram_);
 
   if (insert_before) {
-#if TVM_LLVM_VERSION >= 190
+#if TVM_LLVM_VERSION >= 200
     dbg_info_->di_builder_->insertDeclare(
         llvm_value, local_var, dbg_info_->di_builder_->createExpression(), llvm::DebugLoc(di_loc),
         llvm::BasicBlock::iterator(insert_before));