chore: migrate package name to letta (#1775)

Co-authored-by: Charles Packer <packercharles@gmail.com>
Co-authored-by: Shubham Naik <shubham.naik10@gmail.com>
Co-authored-by: Shubham Naik <shub@memgpt.ai>

.github/ISSUE_TEMPLATE/bug_report.md

@@ -11,11 +11,11 @@ assignees: ''
 A clear and concise description of what the bug is.
 
 **Please describe your setup**
-- [ ] How did you install memgpt?
-  - `pip install pymemgpt`? `pip install pymemgpt-nightly`? `git clone`?
+- [ ] How did you install letta?
+  - `pip install letta`? `pip install letta-nightly`? `git clone`?
 - [ ] Describe your setup
   - What's your OS (Windows/MacOS/Linux)?
-  - How are you running `memgpt`? (`cmd.exe`/Powershell/Anaconda Shell/Terminal)
+  - How are you running `letta`? (`cmd.exe`/Powershell/Anaconda Shell/Terminal)
 
 **Screenshots**
 If applicable, add screenshots to help explain your problem.
@@ -23,8 +23,8 @@ If applicable, add screenshots to help explain your problem.
 **Additional context**
 Add any other context about the problem here.
 
-**MemGPT Config**
-Please attach your `~/.memgpt/config` file or copy past it below.
+**Letta Config**
+Please attach your `~/.letta/config` file or copy past it below.
 
 ---
 
@@ -32,7 +32,7 @@ If you're not using OpenAI, please provide additional information on your local
 
 **Local LLM details**
 
-If you are trying to run MemGPT with local LLMs, please provide the following information:
+If you are trying to run Letta with local LLMs, please provide the following information:
 
 - [ ] The exact model you're trying to use (e.g. `dolphin-2.1-mistral-7b.Q6_K.gguf`)
 - [ ] The local LLM backend you are using (web UI? LM Studio?)